Updating to 0.5 with removing generic_bytes_derive (#150)

Helper generate_nonce to avoid duplicated code + default values for Scrypt

.github/workflows/main.yml

@@ -1,6 +1,8 @@
 name: Rust CI
 on:
   push:
+    branches:
+      - master
   pull_request:
     types: [opened, repoened, synchronize]
 
@@ -13,16 +15,19 @@ jobs:
         backend_feature:
           - u64_backend
           - u32_backend
+        toolchain:
+          - nightly
+          - 1.41.0
     name: test
     steps:
       - name: Checkout sources
         uses: actions/checkout@v2
 
-      - name: Install nightly toolchain
+      - name: Install ${{ matrix.toolchain }} toolchain
         uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: nightly
+          toolchain: ${{ matrix.toolchain }}
           override: true
           components: rustfmt, clippy
 
@@ -32,6 +37,90 @@ jobs:
           command: test
           args: --no-default-features --features ${{ matrix.backend_feature }}
 
+  cross-test:
+    name: Test on ${{ matrix.target }} (using cross)
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        target:
+          # 32-bit x86
+          - i686-unknown-linux-gnu
+        backend_feature:
+          - u64_backend
+          - u32_backend
+    steps:
+      - uses: actions/checkout@v2
+      - uses: hecrj/setup-rust-action@v1
+      - run: cargo install cross
+      # Note: just use `cross` as you would `cargo`, but always
+      # pass the `--target=${{ matrix.target }}` arg. (Yes, really).
+      - run: cross test --verbose --target=${{ matrix.target }} --no-default-features --features ${{ matrix.backend_feature }}
+
+
+  slow-hash-test:
+    name: Test on ${{ matrix.target }} with slow hash
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        backend_feature:
+          - u64_backend
+          - u32_backend
+    steps:
+      - uses: actions/checkout@v2
+      - uses: hecrj/setup-rust-action@v1
+      - run: cargo test --verbose --features slow-hash --no-default-features --features ${{ matrix.backend_feature }}
+
+
+  simple-login-test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        toolchain:
+          - nightly
+          - 1.41.0
+    name: test simple_login command-line example
+    steps:
+      - name: install expect
+        run: sudo apt-get install expect
+      - name: Checkout sources
+        uses: actions/checkout@v2
+      - name: install rust
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.toolchain }}
+          override: true
+          components: rustfmt, clippy
+      - name: Run expect (which then runs cargo run)
+        run: expect -f scripts/simple_login.exp
+
+  digital-locker-test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        toolchain:
+          - nightly
+          - 1.41.0
+    name: test digital_locker command-line example
+    steps:
+      - name: install expect
+        run: sudo apt-get install expect
+      - name: Checkout sources
+        uses: actions/checkout@v2
+      - name: install rust
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.toolchain }}
+          override: true
+          components: rustfmt, clippy
+      - name: Run expect (which then runs cargo run)
+        run: expect -f scripts/digital_locker.exp
+
   benches:
     name: cargo bench compilation
     runs-on: ubuntu-latest
@@ -39,7 +128,7 @@ jobs:
       - name: Checkout sources
         uses: actions/checkout@v2
 
-      - name: Install nightly toolchain
+      - name: Install stable toolchain
         uses: actions-rs/toolchain@v1
         with:
           profile: minimal

.github/workflows/publish.yml

@@ -0,0 +1,29 @@
+name: Publish
+
+on:
+  release:
+    types: [published] # Only publish to crates.io when we formally publish a release
+  # For more on how to formally release on Github, read https://help.github.com/en/articles/creating-releases
+
+jobs:
+  publish:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest]
+
+    steps:
+    - uses: hecrj/setup-rust-action@v1
+      with:
+        rust-version: ${{ matrix.rust }}
+    - uses: actions/checkout@master
+    - name: Login to crates.io
+      run: cargo login $CRATES_IO_TOKEN
+      env:
+        CRATES_IO_TOKEN: ${{ secrets.crates_io_token }} # https://help.github.com/en/actions/automating-your-workflow-with-github-actions/creating-and-using-encrypted-secrets
+    - name: Dry run publish opaque-ke
+      run: cargo publish --dry-run --manifest-path Cargo.toml
+    - name: Publish opaque-ke
+      run: cargo publish --manifest-path Cargo.toml
+      env:
+        CARGO_REGISTRY_TOKEN: ${{ secrets.crates_io_token }}

CHANGELOG.md

@@ -1,5 +1,38 @@
 # Changelog
 
+## 0.5.0 (March 1, 2020)
+
+* Removed dependency on generic-bytes-derive package
+
+## 0.4.0 (February 26, 2020)
+
+* Adherence to protocol format described in
+  https://tools.ietf.org/html/draft-irtf-cfrg-opaque-03
+* Renamed to_bytes() and try_from() to serialize() and deserialize() for
+  top-level structs
+* Conformed all message type parameters to be parameterized in the
+  Ciphersuite object
+
+## 0.3.1 (February 11, 2020)
+
+* Re-exporting the rand library (and including it as a dependency instead of
+  just rand_core)
+* Exposing a convenience function for converting from byte array to Key type
+
+## 0.3.0 (February 8, 2020)
+
+* General API and documentation improvements, including the support of custom
+  identifiers, optional result parameters, and the use of the export key
+* Compliance with RFC 8017 on data serialization functions (I2OSP / OS2IP)
+* Adherence to protocol format described in
+  https://tools.ietf.org/html/draft-irtf-cfrg-opaque-02
+* Added parameters for key exchange additional data
+* Added simple_login and digital_locker examples
+
+## 0.2.1 (October 22, 2020)
+
+* Changed visibility of hash module to be public
+
 ## 0.2.0 (September 3, 2020)
 
 * Added CipherSuite API for specifying underlying primitives

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "opaque-ke"
-version = "0.2.0"
+version = "0.5.0"
 repository = "https://github.com/novifinancial/opaque-ke"
 keywords = ["cryptography", "crypto", "opaque", "passwords", "authentication"]
 description = "An implementation of the OPAQUE password-authenticated key exchange protocol"
@@ -13,34 +13,34 @@ readme = "README.md"
 default = ["u64_backend"]
 slow-hash = ["scrypt"]
 bench = []
-u64_backend = ["curve25519-dalek/u64_backend", "x25519-dalek/u64_backend"]
-u32_backend = ["curve25519-dalek/u32_backend", "x25519-dalek/u32_backend"]
+u64_backend = ["curve25519-dalek/u64_backend"]
+u32_backend = ["curve25519-dalek/u32_backend"]
 
 [dependencies]
 curve25519-dalek = { version = "3.0.0", default-features = false, features = ["std"] }
 digest = "0.9.0"
 displaydoc = "0.1.7"
-fiat-crypto = { version = "0.1.5"}
 generic-array = "0.14.4"
-hkdf = "0.9.0"
-hmac = "0.9.0"
-rand_core = "0.5.1"
-scrypt = { version = "0.4.1", optional = true }
-sha2 = "0.9.1"
-subtle = { version = "^2.2.1", default-features = false }
-thiserror = "1.0.20"
-x25519-dalek = { version = "1.0.1", default-features = false, features = ["std"] }
-zeroize = "1.1"
+generic-bytes = { version = "0.1.0" }
+hkdf = "0.10.0"
+hmac = "0.10.1"
+rand = "0.8"
+scrypt = { version = "0.5.0", optional = true }
+subtle = { version = "2.3.0", default-features = false }
+thiserror = "1.0.22"
+zeroize = "1.1.1"
 
 [dev-dependencies]
-anyhow = "1.0.32"
-base64 = "0.12.3"
+anyhow = "1.0.35"
+base64 = "0.13.0"
+chacha20poly1305 = "0.7.1"
 criterion = "0.3.3"
 hex = "0.4.2"
 lazy_static = "1.4.0"
-serde_json = "1.0.57"
+serde_json = "1.0.60"
+sha2 = "0.9.2"
 proptest = "0.10.1"
-rand = "0.7"
+rustyline = "6.3.0"
 
 [[bench]]
 name = "oprf"

README.md

@@ -22,14 +22,14 @@ Installation
 Add the following line to the dependencies of your `Cargo.toml`:
 
 ```
-opaque-ke = "0.2.0"
+opaque-ke = "0.5.0"
 ```
 
 Resources
 ---------
 
 - [OPAQUE academic publication](https://eprint.iacr.org/2018/163.pdf), including formal definitions and a proof of security
-- [draft-krawczyk-cfrg-opaque-05](https://tools.ietf.org/html/draft-krawczyk-cfrg-opaque-06), containing a specification for the OPAQUE protocol
+- [draft-irtf-cfrg-opaque-03](https://www.ietf.org/archive/id/draft-irtf-cfrg-opaque-03.html), containing a detailed (byte-level) specification for OPAQUE
 - ["Let's talk about PAKE"](https://blog.cryptographyengineering.com/2018/10/19/lets-talk-about-pake/), an introductory blog post written by Matthew Green that covers OPAQUE
 
 Contributors
@@ -41,7 +41,7 @@ To learn more about contributing to this project, [see this document](./CONTRIBU
 
 #### Acknowledgments
 
-Special thanks go to Hugo Krawczyk for helping to clarify discrepancies and making suggestions for improving
+Special thanks go to Hugo Krawczyk and Chris Wood for helping to clarify discrepancies and making suggestions for improving
 this implementation.
 
 

benches/oprf.rs

@@ -7,40 +7,22 @@
 extern crate criterion;
 
 use criterion::Criterion;
-use curve25519_dalek::edwards::EdwardsPoint;
 use curve25519_dalek::ristretto::RistrettoPoint;
 use generic_array::arr;
 use opaque_ke::{
     group::Group,
-    oprf::{generate_oprf1_shim, generate_oprf2_shim, generate_oprf3_shim, OprfClientBytes},
+    oprf::{blind_shim, evaluate_shim, finalize_shim},
 };
 use rand::{prelude::ThreadRng, thread_rng};
-use sha2::Sha256;
+use sha2::Sha512;
 
 fn oprf1(c: &mut Criterion) {
     let mut csprng: ThreadRng = thread_rng();
     let input = b"hunter2";
 
-    c.bench_function("generate_oprf1 with Ristretto", move |b| {
+    c.bench_function("blind with Ristretto", move |b| {
         b.iter(|| {
-            let OprfClientBytes {
-                alpha: _alpha,
-                blinding_factor: _blinding_factor,
-            } = generate_oprf1_shim::<_, RistrettoPoint>(&input[..], None, &mut csprng).unwrap();
-        })
-    });
-}
-
-fn oprf1_edwards(c: &mut Criterion) {
-    let mut csprng: ThreadRng = thread_rng();
-    let input = b"hunter2";
-
-    c.bench_function("generate_oprf1 with Edwards", move |b| {
-        b.iter(|| {
-            let OprfClientBytes {
-                alpha: _alpha,
-                blinding_factor: _blinding_factor,
-            } = generate_oprf1_shim::<_, EdwardsPoint>(&input[..], None, &mut csprng).unwrap();
+            blind_shim::<_, RistrettoPoint, Sha512>(&input[..], &mut csprng).unwrap();
         })
     });
 }
@@ -49,40 +31,16 @@ fn oprf2(c: &mut Criterion) {
     let mut csprng: ThreadRng = thread_rng();
     let input = b"hunter2";
 
-    let OprfClientBytes {
-        alpha,
-        blinding_factor: _blinding_factor,
-    } = generate_oprf1_shim::<_, RistrettoPoint>(&input[..], None, &mut csprng).unwrap();
+    let (_, alpha) = blind_shim::<_, RistrettoPoint, Sha512>(&input[..], &mut csprng).unwrap();
     let salt_bytes = arr![
         u8; 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
         24, 25, 26, 27, 28, 29, 30, 31, 32,
     ];
     let salt = RistrettoPoint::from_scalar_slice(&salt_bytes).unwrap();
 
-    c.bench_function("generate_oprf2 with Ristretto", move |b| {
+    c.bench_function("evaluate with Ristretto", move |b| {
         b.iter(|| {
-            let _beta = generate_oprf2_shim::<RistrettoPoint>(alpha, &salt).unwrap();
-        })
-    });
-}
-
-fn oprf2_edwards(c: &mut Criterion) {
-    let mut csprng: ThreadRng = thread_rng();
-    let input = b"hunter2";
-
-    let OprfClientBytes {
-        alpha,
-        blinding_factor: _blinding_factor,
-    } = generate_oprf1_shim::<_, EdwardsPoint>(&input[..], None, &mut csprng).unwrap();
-    let salt_bytes = arr![
-        u8; 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
-        24, 25, 26, 27, 28, 29, 30, 31, 32,
-    ];
-    let salt = RistrettoPoint::from_scalar_slice(&salt_bytes).unwrap();
-
-    c.bench_function("generate_oprf2 with Edwards", move |b| {
-        b.iter(|| {
-            let _beta = generate_oprf2_shim::<EdwardsPoint>(alpha, &salt).unwrap();
+            let _beta = evaluate_shim::<RistrettoPoint>(alpha, &salt);
         })
     });
 }
@@ -91,55 +49,20 @@ fn oprf3(c: &mut Criterion) {
     let mut csprng: ThreadRng = thread_rng();
     let input = b"hunter2";
 
-    let OprfClientBytes {
-        alpha,
-        blinding_factor,
-    } = generate_oprf1_shim::<_, RistrettoPoint>(&input[..], None, &mut csprng).unwrap();
+    let (token, alpha) = blind_shim::<_, RistrettoPoint, Sha512>(&input[..], &mut csprng).unwrap();
     let salt_bytes = arr![
         u8; 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
         24, 25, 26, 27, 28, 29, 30, 31, 32,
     ];
     let salt = RistrettoPoint::from_scalar_slice(&salt_bytes).unwrap();
-    let beta = generate_oprf2_shim::<RistrettoPoint>(alpha, &salt).unwrap();
+    let beta = evaluate_shim::<RistrettoPoint>(alpha, &salt);
 
-    c.bench_function("generate_oprf3 with Ristretto", move |b| {
+    c.bench_function("finalize with Ristretto", move |b| {
         b.iter(|| {
-            let _res = generate_oprf3_shim::<RistrettoPoint, Sha256>(input, beta, &blinding_factor)
-                .unwrap();
+            let _res = finalize_shim::<RistrettoPoint, Sha512>(&token, beta).unwrap();
         })
     });
 }
 
-fn oprf3_edwards(c: &mut Criterion) {
-    let mut csprng: ThreadRng = thread_rng();
-    let input = b"hunter2";
-
-    let OprfClientBytes {
-        alpha,
-        blinding_factor,
-    } = generate_oprf1_shim::<_, EdwardsPoint>(&input[..], None, &mut csprng).unwrap();
-    let salt_bytes = arr![
-        u8; 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
-        24, 25, 26, 27, 28, 29, 30, 31, 32,
-    ];
-    let salt = RistrettoPoint::from_scalar_slice(&salt_bytes).unwrap();
-    let beta = generate_oprf2_shim::<EdwardsPoint>(alpha, &salt).unwrap();
-
-    c.bench_function("generate_oprf3 with Edwards", move |b| {
-        b.iter(|| {
-            let _res =
-                generate_oprf3_shim::<EdwardsPoint, Sha256>(input, beta, &blinding_factor).unwrap();
-        })
-    });
-}
-
-criterion_group!(
-    oprf_benches,
-    oprf1,
-    oprf2,
-    oprf3,
-    oprf1_edwards,
-    oprf2_edwards,
-    oprf3_edwards
-);
+criterion_group!(oprf_benches, oprf1, oprf2, oprf3);
 criterion_main!(oprf_benches);

deny.toml

@@ -34,7 +34,7 @@ targets = [
 # The path where the advisory database is cloned/fetched into
 db-path = "~/.cargo/advisory-db"
 # The url of the advisory database to use
-db-url = "https://github.com/rustsec/advisory-db"
+db-urls = ["https://github.com/rustsec/advisory-db"]
 # The lint level for security vulnerabilities
 vulnerability = "deny"
 # The lint level for unmaintained crates

examples/digital_locker.rs

@@ -0,0 +1,326 @@
+// Copyright (c) Facebook, Inc. and its affiliates.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+//! Demonstrates an implementation of a server-side secured digital locker using
+//! the client's OPAQUE export key, over a command-line interface
+//!
+//! A client can password-protect a secret message to be stored in a digital locker,
+//! controlled by the server. The locker's contents are only revealed to the holder
+//! of the password when attempting to open the locker.
+//!
+//! The client-server interactions are executed in a three-step protocol
+//! within the account_registration (for password registration) and
+//! account_login (for password login) functions. These steps
+//! must be performed in the specific sequence outlined in each of these
+//! functions.
+//!
+//! The CipherSuite trait allows the application to configure the
+//! primitives used by OPAQUE, but must be kept consistent across the steps
+//! of the protocol.
+//!
+//! In a more realistic client-server interaction, the client must send
+//! messages over "the wire" to the server. These bytes are serialized
+//! and explicitly annotated in the below functions.
+
+use chacha20poly1305::aead::{Aead, NewAead};
+use chacha20poly1305::{ChaCha20Poly1305, Key, Nonce};
+use rustyline::error::ReadlineError;
+use rustyline::Editor;
+use std::process::exit;
+
+use opaque_ke::{
+    ciphersuite::CipherSuite,
+    rand::{rngs::OsRng, RngCore},
+    ClientLogin, ClientLoginFinishParameters, ClientLoginStartParameters, ClientRegistration,
+    ClientRegistrationFinishParameters, CredentialFinalization, CredentialRequest,
+    CredentialResponse, RegistrationRequest, RegistrationResponse, RegistrationUpload, ServerLogin,
+    ServerLoginStartParameters, ServerRegistration,
+};
+
+// The ciphersuite trait allows to specify the underlying primitives
+// that will be used in the OPAQUE protocol
+#[allow(dead_code)]
+struct Default;
+impl CipherSuite for Default {
+    type Group = curve25519_dalek::ristretto::RistrettoPoint;
+    type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
+    type Hash = sha2::Sha512;
+    type SlowHash = opaque_ke::slow_hash::NoOpHash;
+}
+
+struct Locker {
+    contents: Vec<u8>,
+    password_file: Vec<u8>,
+}
+
+// Given a key and plaintext, produce an AEAD ciphertext along with a nonce
+fn encrypt(key: &[u8], plaintext: &[u8]) -> Vec<u8> {
+    let cipher = ChaCha20Poly1305::new(Key::from_slice(&key[..32]));
+
+    let mut rng = OsRng;
+    let mut nonce_bytes = [0u8; 12];
+    rng.fill_bytes(&mut nonce_bytes);
+    let nonce = Nonce::from_slice(&nonce_bytes);
+
+    let ciphertext = cipher.encrypt(nonce, plaintext.as_ref()).unwrap();
+    [nonce_bytes.to_vec(), ciphertext].concat()
+}
+
+// Decrypt using a key and a ciphertext (nonce included) to recover the original plaintext
+fn decrypt(key: &[u8], ciphertext: &[u8]) -> Vec<u8> {
+    let cipher = ChaCha20Poly1305::new(Key::from_slice(&key[..32]));
+    cipher
+        .decrypt(
+            Nonce::from_slice(&ciphertext[..12]),
+            ciphertext[12..].as_ref(),
+        )
+        .unwrap()
+}
+
+// Password-based registration and encryption of client secret message between a client and server
+fn register_locker(
+    server_kp: &opaque_ke::keypair::KeyPair<curve25519_dalek::ristretto::RistrettoPoint>,
+    password: String,
+    secret_message: String,
+) -> Locker {
+    let mut client_rng = OsRng;
+    let client_registration_start_result =
+        ClientRegistration::<Default>::start(&mut client_rng, password.as_bytes()).unwrap();
+    let registration_request_bytes = client_registration_start_result.message.serialize();
+
+    // Client sends registration_request_bytes to server
+
+    let mut server_rng = OsRng;
+    let server_registration_start_result = ServerRegistration::<Default>::start(
+        &mut server_rng,
+        RegistrationRequest::deserialize(&registration_request_bytes[..]).unwrap(),
+        server_kp.public(),
+    )
+    .unwrap();
+    let registration_response_bytes = server_registration_start_result.message.serialize();
+
+    // Server sends registration_response_bytes to client
+
+    let client_finish_registration_result = client_registration_start_result
+        .state
+        .finish(
+            &mut client_rng,
+            RegistrationResponse::deserialize(&registration_response_bytes[..]).unwrap(),
+            ClientRegistrationFinishParameters::default(),
+        )
+        .unwrap();
+    let message_bytes = client_finish_registration_result.message.serialize();
+
+    // Client encrypts secret message using export key
+    let ciphertext = encrypt(
+        &client_finish_registration_result.export_key,
+        secret_message.as_bytes(),
+    );
+
+    // Client sends message_bytes to server
+
+    let password_file = server_registration_start_result
+        .state
+        .finish(RegistrationUpload::deserialize(&message_bytes[..]).unwrap())
+        .unwrap();
+
+    Locker {
+        contents: ciphertext,
+        password_file: password_file.serialize(),
+    }
+}
+
+// Open the contents of a locker with a password between a client and server
+fn open_locker(
+    server_kp: &opaque_ke::keypair::KeyPair<curve25519_dalek::ristretto::RistrettoPoint>,
+    password: String,
+    locker: &Locker,
+) -> Result<String, String> {
+    let mut client_rng = OsRng;
+    let client_login_start_result = ClientLogin::<Default>::start(
+        &mut client_rng,
+        password.as_bytes(),
+        ClientLoginStartParameters::default(),
+    )
+    .unwrap();
+    let credential_request_bytes = client_login_start_result.message.serialize();
+
+    // Client sends credential_request_bytes to server
+
+    let password_file =
+        ServerRegistration::<Default>::deserialize(&locker.password_file[..]).unwrap();
+    let mut server_rng = OsRng;
+    let server_login_start_result = ServerLogin::start(
+        &mut server_rng,
+        password_file,
+        &server_kp.private(),
+        CredentialRequest::deserialize(&credential_request_bytes[..]).unwrap(),
+        ServerLoginStartParameters::default(),
+    )
+    .unwrap();
+    let credential_response_bytes = server_login_start_result.message.serialize();
+
+    // Server sends credential_response_bytes to client
+
+    let result = client_login_start_result.state.finish(
+        CredentialResponse::deserialize(&credential_response_bytes[..]).unwrap(),
+        ClientLoginFinishParameters::default(),
+    );
+
+    if result.is_err() {
+        // Client-detected login failure
+        return Err(String::from("Incorrect password, please try again."));
+    }
+    let client_login_finish_result = result.unwrap();
+    let credential_finalization_bytes = client_login_finish_result.message.serialize();
+
+    // Client sends credential_finalization_bytes to server
+
+    let server_login_finish_result = server_login_start_result
+        .state
+        .finish(CredentialFinalization::deserialize(&credential_finalization_bytes[..]).unwrap())
+        .unwrap();
+
+    // Server sends locker contents, encrypted under the session key, to the client
+    let encrypted_locker_contents =
+        encrypt(&server_login_finish_result.session_key, &locker.contents);
+
+    // Client decrypts contents of locker, first under the session key, and then under the export key
+    let plaintext = decrypt(
+        &client_login_finish_result.export_key,
+        &decrypt(
+            &client_login_finish_result.session_key,
+            &encrypted_locker_contents,
+        ),
+    );
+    String::from_utf8(plaintext).map_err(|_| String::from("UTF8 error"))
+}
+
+fn main() {
+    let mut rng = OsRng;
+    let server_kp = Default::generate_random_keypair(&mut rng);
+
+    let mut rl = Editor::<()>::new();
+    let mut registered_lockers: Vec<Locker> = vec![];
+    loop {
+        display_lockers(&registered_lockers);
+
+        println!("Enter an option (1 or 2):");
+        println!("1) Register a locker");
+        println!("2) Open a locker\n");
+        let readline = rl.readline("> ");
+        match readline {
+            Ok(line) => {
+                if line != "1" && line != "2" {
+                    println!("Error: Invalid option (either specify 1 or 2)");
+                    continue;
+                }
+                match line.as_ref() {
+                    "1" => {
+                        let (password, secret_message) = get_two_strings(
+                            "Choose a password",
+                            "Set a secret message",
+                            &mut rl,
+                            None,
+                        );
+                        registered_lockers.push(register_locker(
+                            &server_kp,
+                            password,
+                            secret_message,
+                        ));
+                        continue;
+                    }
+                    "2" => {
+                        let (locker, password) = get_two_strings(
+                            "Choose a locker number",
+                            "Enter the password",
+                            &mut rl,
+                            None,
+                        );
+                        let locker_index: usize = match locker.parse() {
+                            Ok(index) => index,
+                            Err(_) => {
+                                println!("Error: Could not find locker number");
+                                continue;
+                            }
+                        };
+
+                        if locker_index >= registered_lockers.len() {
+                            println!("Error: Could not find locker number");
+                            continue;
+                        }
+
+                        match open_locker(&server_kp, password, &registered_lockers[locker_index]) {
+                            Ok(contents) => {
+                                println!("\n\nSuccess! Contents: {}\n\n", contents);
+                            }
+                            Err(err) => {
+                                println!(
+                                    "\n\nError encountered, could not open locker: {}\n\n",
+                                    err
+                                );
+                            }
+                        }
+                    }
+                    _ => exit(0),
+                }
+            }
+            Err(err) => {
+                handle_error(err);
+                exit(0)
+            }
+        }
+    }
+}
+
+// Helper functions
+
+fn display_lockers(lockers: &Vec<Locker>) {
+    let mut locker_numbers = vec![];
+    for (i, _) in lockers.iter().enumerate() {
+        locker_numbers.push(i);
+    }
+
+    println!(
+        "\nCurrently registered locker numbers: {:?}\n",
+        locker_numbers
+    );
+}
+
+// Handle readline errors
+fn handle_error(err: ReadlineError) {
+    match err {
+        ReadlineError::Interrupted => {
+            println!("CTRL-C");
+        }
+        ReadlineError::Eof => {
+            println!("CTRL-D");
+        }
+        err => {
+            println!("Error: {:?}", err);
+        }
+    }
+}
+
+// A function run on the client which extracts two strings from the CLI
+fn get_two_strings(
+    s1: &str,
+    s2: &str,
+    rl: &mut Editor<()>,
+    string1: Option<String>,
+) -> (String, String) {
+    let query = if string1.is_none() { s1 } else { s2 };
+    let readline = rl.readline(&format!("{}: ", query));
+    match readline {
+        Ok(line) => match string1 {
+            Some(x) => (x, line),
+            None => get_two_strings(s1, s2, rl, Some(line)),
+        },
+        Err(err) => {
+            handle_error(err);
+            exit(0)
+        }
+    }
+}

examples/simple_login.rs

@@ -0,0 +1,233 @@
+// Copyright (c) Facebook, Inc. and its affiliates.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+//! Demonstrates a simple client-server password-based login protocol
+//! using OPAQUE, over a command-line interface
+//!
+//! The client-server interactions are executed in a three-step protocol
+//! within the account_registration (for password registration) and
+//! account_login (for password login) functions. These steps
+//! must be performed in the specific sequence outlined in each of these
+//! functions.
+//!
+//! The CipherSuite trait allows the application to configure the
+//! primitives used by OPAQUE, but must be kept consistent across the steps
+//! of the protocol.
+//!
+//! In a more realistic client-server interaction, the client must send
+//! messages over "the wire" to the server. These bytes are serialized
+//! and explicitly annotated in the below functions.
+
+use rustyline::error::ReadlineError;
+use rustyline::Editor;
+use std::collections::HashMap;
+use std::process::exit;
+
+use opaque_ke::{
+    ciphersuite::CipherSuite, rand::rngs::OsRng, ClientLogin, ClientLoginFinishParameters,
+    ClientLoginStartParameters, ClientRegistration, ClientRegistrationFinishParameters,
+    CredentialFinalization, CredentialRequest, CredentialResponse, RegistrationRequest,
+    RegistrationResponse, RegistrationUpload, ServerLogin, ServerLoginStartParameters,
+    ServerRegistration,
+};
+
+// The ciphersuite trait allows to specify the underlying primitives
+// that will be used in the OPAQUE protocol
+#[allow(dead_code)]
+struct Default;
+impl CipherSuite for Default {
+    type Group = curve25519_dalek::ristretto::RistrettoPoint;
+    type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
+    type Hash = sha2::Sha512;
+    type SlowHash = opaque_ke::slow_hash::NoOpHash;
+}
+
+// Password-based registration between a client and server
+fn account_registration(
+    server_kp: &opaque_ke::keypair::KeyPair<curve25519_dalek::ristretto::RistrettoPoint>,
+    password: String,
+) -> Vec<u8> {
+    let mut client_rng = OsRng;
+    let client_registration_start_result =
+        ClientRegistration::<Default>::start(&mut client_rng, password.as_bytes()).unwrap();
+    let registration_request_bytes = client_registration_start_result.message.serialize();
+
+    // Client sends registration_request_bytes to server
+
+    let mut server_rng = OsRng;
+    let server_registration_start_result = ServerRegistration::<Default>::start(
+        &mut server_rng,
+        RegistrationRequest::deserialize(&registration_request_bytes[..]).unwrap(),
+        server_kp.public(),
+    )
+    .unwrap();
+    let registration_response_bytes = server_registration_start_result.message.serialize();
+
+    // Server sends registration_response_bytes to client
+
+    let client_finish_registration_result = client_registration_start_result
+        .state
+        .finish(
+            &mut client_rng,
+            RegistrationResponse::deserialize(&registration_response_bytes[..]).unwrap(),
+            ClientRegistrationFinishParameters::default(),
+        )
+        .unwrap();
+    let message_bytes = client_finish_registration_result.message.serialize();
+
+    // Client sends message_bytes to server
+
+    let password_file = server_registration_start_result
+        .state
+        .finish(RegistrationUpload::deserialize(&message_bytes[..]).unwrap())
+        .unwrap();
+    password_file.serialize()
+}
+
+// Password-based login between a client and server
+fn account_login(
+    server_kp: &opaque_ke::keypair::KeyPair<curve25519_dalek::ristretto::RistrettoPoint>,
+    password: String,
+    password_file_bytes: &[u8],
+) -> bool {
+    let mut client_rng = OsRng;
+    let client_login_start_result = ClientLogin::<Default>::start(
+        &mut client_rng,
+        password.as_bytes(),
+        ClientLoginStartParameters::default(),
+    )
+    .unwrap();
+    let credential_request_bytes = client_login_start_result.message.serialize();
+
+    // Client sends credential_request_bytes to server
+
+    let password_file = ServerRegistration::<Default>::deserialize(password_file_bytes).unwrap();
+    let mut server_rng = OsRng;
+    let server_login_start_result = ServerLogin::start(
+        &mut server_rng,
+        password_file,
+        &server_kp.private(),
+        CredentialRequest::deserialize(&credential_request_bytes[..]).unwrap(),
+        ServerLoginStartParameters::default(),
+    )
+    .unwrap();
+    let credential_response_bytes = server_login_start_result.message.serialize();
+
+    // Server sends credential_response_bytes to client
+
+    let result = client_login_start_result.state.finish(
+        CredentialResponse::deserialize(&credential_response_bytes[..]).unwrap(),
+        ClientLoginFinishParameters::default(),
+    );
+
+    if result.is_err() {
+        // Client-detected login failure
+        return false;
+    }
+    let client_login_finish_result = result.unwrap();
+    let credential_finalization_bytes = client_login_finish_result.message.serialize();
+
+    // Client sends credential_finalization_bytes to server
+
+    let server_login_finish_result = server_login_start_result
+        .state
+        .finish(CredentialFinalization::deserialize(&credential_finalization_bytes[..]).unwrap())
+        .unwrap();
+
+    client_login_finish_result.session_key == server_login_finish_result.session_key
+}
+
+fn main() {
+    let mut rng = OsRng;
+    let server_kp = Default::generate_random_keypair(&mut rng);
+
+    let mut rl = Editor::<()>::new();
+    let mut registered_users = HashMap::<String, Vec<u8>>::new();
+    loop {
+        println!(
+            "\nCurrently registered usernames: {:?}\n",
+            registered_users.keys()
+        );
+
+        println!("Enter an option (1 or 2):");
+        println!("1) Register a user");
+        println!("2) Login as a user\n");
+        let readline = rl.readline("> ");
+        match readline {
+            Ok(line) => {
+                if line != "1" && line != "2" {
+                    println!("Error: Invalid option (either specify 1 or 2)");
+                    continue;
+                }
+                let (username, password) = get_two_strings("Username", "Password", &mut rl, None);
+                match line.as_ref() {
+                    "1" => {
+                        registered_users
+                            .insert(username, account_registration(&server_kp, password));
+                        continue;
+                    }
+                    "2" => match registered_users.get(&username) {
+                        Some(password_file_bytes) => {
+                            if account_login(&server_kp, password, password_file_bytes) {
+                                println!("\nLogin success!");
+                            } else {
+                                // Note that at this point, the client knows whether or not the login
+                                // succeeded. In this example, we simply rely on client-reported result
+                                // of login, but in a real client-server implementation, the server may not
+                                // know the outcome of login yet, and extra care must be taken to ensure
+                                // that the server can learn the outcome as well.
+                                println!("\nIncorrect password, please try again.");
+                            }
+                        }
+                        None => println!("Error: Could not find username registered"),
+                    },
+                    _ => exit(0),
+                }
+            }
+            Err(err) => {
+                handle_error(err);
+                exit(0)
+            }
+        }
+    }
+}
+
+// Helper functions
+
+// Handle readline errors
+fn handle_error(err: ReadlineError) {
+    match err {
+        ReadlineError::Interrupted => {
+            println!("CTRL-C");
+        }
+        ReadlineError::Eof => {
+            println!("CTRL-D");
+        }
+        err => {
+            println!("Error: {:?}", err);
+        }
+    }
+}
+
+// A function run on the client which extracts two strings from the CLI
+fn get_two_strings(
+    s1: &str,
+    s2: &str,
+    rl: &mut Editor<()>,
+    string1: Option<String>,
+) -> (String, String) {
+    let query = if string1.is_none() { s1 } else { s2 };
+    let readline = rl.readline(&format!("{}: ", query));
+    match readline {
+        Ok(line) => match string1 {
+            Some(x) => (x, line),
+            None => get_two_strings(s1, s2, rl, Some(line)),
+        },
+        Err(err) => {
+            handle_error(err);
+            exit(0)
+        }
+    }
+}

scripts/digital_locker.exp

@@ -0,0 +1,84 @@
+#!/bin/expect -f
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+set timeout 1
+spawn cargo run --example digital_locker
+match_max 100000
+sleep 1
+expect "*
+\r
+Currently registered locker numbers: \\\[\\\]\r
+\r
+Enter an option (1 or 2):\r
+1) Register a locker\r
+2) Open a locker\r
+\r
+"
+sleep .1
+send -- "1\r"
+expect "Choose a password: \r"
+send -- "foo\r"
+expect "Set a secret message: \r"
+send -- "bar\r"
+expect "*
+\r
+Currently registered locker numbers: \\\[0\\\]\r
+\r
+Enter an option (1 or 2):\r
+1) Register a locker\r
+2) Open a locker\r
+\r
+"
+sleep .1
+send -- "2\r"
+expect "Choose a locker number: \r"
+send -- "1\r"
+expect "Password: \r"
+send -- "foo\r"
+expect "*Error: Could not find locker number\r
+\r
+Currently registered locker numbers: \\\[0\\\]\r
+\r
+Enter an option (1 or 2):\r
+1) Register a locker\r
+2) Open a locker\r
+\r
+"
+sleep .1
+send -- "2\r"
+expect "Choose a locker number: \r"
+send -- "0\r"
+expect "Password: \r"
+send -- "baz\r"
+expect "*Error encountered, could not open locker: Incorrect password, please try again.\r
+\r
+Currently registered locker numbers: \\\[0\\\]\r
+\r
+Enter an option (1 or 2):\r
+1) Register a locker\r
+2) Open a locker\r
+\r
+"
+sleep .1
+send -- "2\r"
+expect "Choose a locker number: \r"
+send -- "0\r"
+expect "Password: \r"
+send -- "foo\r"
+expect "*
+\r
+*Success! Contents: bar\r
+\r
+Currently registered locker numbers: \\\[0\\\]\r
+\r
+Enter an option (1 or 2):\r
+1) Register a locker\r
+2) Open a locker\r
+\r
+"
+sleep .1
+send -- ""
+expect eof

scripts/simple_login.exp

@@ -0,0 +1,84 @@
+#!/bin/expect -f
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+set timeout 1
+spawn cargo run --example simple_login
+match_max 100000
+sleep 1
+expect "*
+\r
+Currently registered usernames: \\\[\\\]\r
+\r
+Enter an option (1 or 2):\r
+1) Register a user\r
+2) Login as a user\r
+\r
+"
+sleep .1
+send -- "1\r"
+expect "Username: \r"
+send -- "foo\r"
+expect "Password: \r"
+send -- "bar\r"
+expect "*
+\r
+Currently registered usernames: \\\[\"foo\"\\\]\r
+\r
+Enter an option (1 or 2):\r
+1) Register a user\r
+2) Login as a user\r
+\r
+"
+sleep .1
+send -- "2\r"
+expect "Username: \r"
+send -- "baz\r"
+expect "Password: \r"
+send -- "quux\r"
+expect "*Error: Could not find username registered\r
+\r
+Currently registered usernames: \\\[\"foo\"\\\]\r
+\r
+Enter an option (1 or 2):\r
+1) Register a user\r
+2) Login as a user\r
+\r
+"
+sleep .1
+send -- "2\r"
+expect "Username: \r"
+send -- "foo\r"
+expect "Password: \r"
+send -- "baz\r"
+expect "*Incorrect password, please try again.\r
+\r
+Currently registered usernames: \\\[\"foo\"\\\]\r
+\r
+Enter an option (1 or 2):\r
+1) Register a user\r
+2) Login as a user\r
+\r
+"
+sleep .1
+send -- "2\r"
+expect "Username: \r"
+send -- "foo\r"
+expect "Password: \r"
+send -- "bar\r"
+expect "*
+\r
+*Login success!\r
+\r
+Currently registered usernames: \\\[\"foo\"\\\]\r
+\r
+Enter an option (1 or 2):\r
+1) Register a user\r
+2) Login as a user\r
+\r
+"
+sleep .1
+send -- ""
+expect eof

src/ciphersuite.rs

@@ -6,22 +6,18 @@
 //! Defines the CipherSuite trait to specify the underlying primitives for OPAQUE
 
 use crate::{
-    errors::InternalPakeError,
-    hash::Hash,
-    key_exchange::traits::KeyExchange,
-    keypair::{Key, KeyPair},
-    map_to_curve::GroupWithMapToCurve,
-    slow_hash::SlowHash,
+    hash::Hash, key_exchange::traits::KeyExchange, keypair::KeyPair,
+    map_to_curve::GroupWithMapToCurve, slow_hash::SlowHash,
 };
+use digest::Digest;
 
-use rand_core::{CryptoRng, RngCore};
+use rand::{CryptoRng, RngCore};
 
 /// Configures the underlying primitives used in OPAQUE
 /// * `Group`: a finite cyclic group along with a point representation, along
 ///   with an extension trait PasswordToCurve that allows some customization on
 ///   how to hash a password to a curve point. See `group::Group` and
 ///   `map_to_curve::GroupWithMapToCurve`.
-/// * `KeyFormat`: a keypair type composed of public and private components
 /// * `KeyExchange`: The key exchange protocol to use in the login step
 /// * `Hash`: The main hashing function to use
 /// * `SlowHash`: A slow hashing function, typically used for password hashing
@@ -30,19 +26,16 @@ pub trait CipherSuite {
     /// an extension trait PasswordToCurve that allows some customization on
     /// how to hash a password to a curve point. See `group::Group` and
     /// `map_to_curve::GroupWithMapToCurve`.
-    type Group: GroupWithMapToCurve;
-    /// A keypair type composed of public and private components
-    type KeyFormat: KeyPair<Repr = Key> + PartialEq;
+    type Group: GroupWithMapToCurve<UniformBytesLen = <Self::Hash as Digest>::OutputSize>;
     /// A key exchange protocol
-    type KeyExchange: KeyExchange<Self::Hash>;
+    type KeyExchange: KeyExchange<Self::Hash, Self::Group>;
     /// The main hash function use (for HKDF computations and hashing transcripts)
     type Hash: Hash;
     /// A slow hashing function, typically used for password hashing
     type SlowHash: SlowHash<Self::Hash>;
+
     /// Generating a random key pair given a cryptographic rng
-    fn generate_random_keypair<R: RngCore + CryptoRng>(
-        rng: &mut R,
-    ) -> Result<Self::KeyFormat, InternalPakeError> {
-        Self::KeyFormat::generate_random(rng)
+    fn generate_random_keypair<R: RngCore + CryptoRng>(rng: &mut R) -> KeyPair<Self::Group> {
+        KeyPair::<Self::Group>::generate_random(rng)
     }
 }

src/elligator/field.rs

@@ -1,353 +0,0 @@
-// Copyright (c) Facebook, Inc. and its affiliates.
-//
-// This source code is licensed under the MIT license found in the
-// LICENSE file in the root directory of this source tree.
-#![allow(clippy::let_and_return)]
-
-//! Field arithmetic modulo \\(p = 2\^{255} - 19\\), using \\(64\\)-bit
-//! limbs with \\(128\\)-bit products.
-
-use core::fmt::Debug;
-use core::ops::Neg;
-use core::ops::{Add, AddAssign};
-use core::ops::{Mul, MulAssign};
-
-use subtle::Choice;
-use subtle::ConditionallyNegatable;
-use subtle::ConditionallySelectable;
-use subtle::ConstantTimeEq;
-
-use zeroize::Zeroize;
-
-use fiat_crypto::curve25519_64::*;
-
-/// A `FieldElement51` represents an element of the field
-/// \\( \mathbb Z / (2\^{255} - 19)\\).
-///
-/// In the 64-bit implementation, a `FieldElement` is represented in
-/// radix \\(2\^{51}\\) as five `u64`s; the coefficients are allowed to
-/// grow up to \\(2\^{54}\\) between reductions modulo \\(p\\).
-///
-/// # Note
-///
-/// The `curve25519_dalek::field` module provides a type alias
-/// `curve25519_dalek::field::FieldElement` to either `FieldElement51`
-/// or `FieldElement2625`.
-///
-/// The backend-specific type `FieldElement51` should not be used
-/// outside of the `curve25519_dalek::field` module.
-#[derive(Copy, Clone)]
-pub struct FieldElement51(pub(crate) [u64; 5]);
-
-impl Debug for FieldElement51 {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
-        write!(f, "FieldElement51({:?})", &self.0[..])
-    }
-}
-
-impl Zeroize for FieldElement51 {
-    fn zeroize(&mut self) {
-        self.0.zeroize();
-    }
-}
-
-impl ConstantTimeEq for FieldElement51 {
-    /// Test equality between two `FieldElement`s.  Since the
-    /// internal representation is not canonical, the field elements
-    /// are normalized to wire format before comparison.
-    fn ct_eq(&self, other: &FieldElement51) -> Choice {
-        self.to_bytes().ct_eq(&other.to_bytes())
-    }
-}
-
-impl<'b> AddAssign<&'b FieldElement51> for FieldElement51 {
-    fn add_assign(&mut self, _rhs: &'b FieldElement51) {
-        let input = self.0;
-        fiat_25519_add(&mut self.0, &input, &_rhs.0);
-        let input = self.0;
-        fiat_25519_carry(&mut self.0, &input);
-    }
-}
-
-impl<'a, 'b> Add<&'b FieldElement51> for &'a FieldElement51 {
-    type Output = FieldElement51;
-    fn add(self, _rhs: &'b FieldElement51) -> FieldElement51 {
-        let mut output = *self;
-        fiat_25519_add(&mut output.0, &self.0, &_rhs.0);
-        let input = output.0;
-        fiat_25519_carry(&mut output.0, &input);
-        output
-    }
-}
-
-impl<'b> MulAssign<&'b FieldElement51> for FieldElement51 {
-    fn mul_assign(&mut self, _rhs: &'b FieldElement51) {
-        let input = self.0;
-        fiat_25519_carry_mul(&mut self.0, &input, &_rhs.0);
-    }
-}
-
-impl<'a, 'b> Mul<&'b FieldElement51> for &'a FieldElement51 {
-    type Output = FieldElement51;
-    fn mul(self, _rhs: &'b FieldElement51) -> FieldElement51 {
-        let mut output = *self;
-        fiat_25519_carry_mul(&mut output.0, &self.0, &_rhs.0);
-        output
-    }
-}
-
-impl<'a> Neg for &'a FieldElement51 {
-    type Output = FieldElement51;
-    fn neg(self) -> FieldElement51 {
-        let mut output = *self;
-        fiat_25519_opp(&mut output.0, &self.0);
-        let input = output.0;
-        fiat_25519_carry(&mut output.0, &input);
-        output
-    }
-}
-
-impl ConditionallySelectable for FieldElement51 {
-    fn conditional_select(
-        a: &FieldElement51,
-        b: &FieldElement51,
-        choice: Choice,
-    ) -> FieldElement51 {
-        let mut output = [0u64; 5];
-        fiat_25519_selectznz(&mut output, choice.unwrap_u8() as fiat_25519_u1, &a.0, &b.0);
-        FieldElement51(output)
-    }
-
-    fn conditional_swap(a: &mut FieldElement51, b: &mut FieldElement51, choice: Choice) {
-        u64::conditional_swap(&mut a.0[0], &mut b.0[0], choice);
-        u64::conditional_swap(&mut a.0[1], &mut b.0[1], choice);
-        u64::conditional_swap(&mut a.0[2], &mut b.0[2], choice);
-        u64::conditional_swap(&mut a.0[3], &mut b.0[3], choice);
-        u64::conditional_swap(&mut a.0[4], &mut b.0[4], choice);
-    }
-
-    fn conditional_assign(&mut self, _rhs: &FieldElement51, choice: Choice) {
-        let mut output = [0u64; 5];
-        let choicebit = choice.unwrap_u8() as fiat_25519_u1;
-        fiat_25519_cmovznz_u64(&mut output[0], choicebit, self.0[0], _rhs.0[0]);
-        fiat_25519_cmovznz_u64(&mut output[1], choicebit, self.0[1], _rhs.0[1]);
-        fiat_25519_cmovznz_u64(&mut output[2], choicebit, self.0[2], _rhs.0[2]);
-        fiat_25519_cmovznz_u64(&mut output[3], choicebit, self.0[3], _rhs.0[3]);
-        fiat_25519_cmovznz_u64(&mut output[4], choicebit, self.0[4], _rhs.0[4]);
-        *self = FieldElement51(output);
-    }
-}
-
-impl FieldElement51 {
-    /// Construct zero.
-    pub fn zero() -> FieldElement51 {
-        FieldElement51([0, 0, 0, 0, 0])
-    }
-
-    /// Construct one.
-    pub fn one() -> FieldElement51 {
-        FieldElement51([1, 0, 0, 0, 0])
-    }
-
-    pub fn is_negative(&self) -> Choice {
-        let bytes = self.to_bytes();
-        (bytes[0] & 1).into()
-    }
-
-    /// Raise this field element to the power (p-5)/8 = 2^252 -3.
-    fn pow_p58(&self) -> FieldElement51 {
-        // The bits of (p-5)/8 are 101111.....11.
-        //
-        //                                 nonzero bits of exponent
-        let (t19, _) = self.pow22501(); // 249..0
-        let t20 = t19.pow2k(2); // 251..2
-        let t21 = self * &t20; // 251..2,0
-
-        t21
-    }
-
-    /// Given a nonzero field element, compute its inverse.
-    ///
-    /// The inverse is computed as self^(p-2), since
-    /// x^(p-2)x = x^(p-1) = 1 (mod p).
-    ///
-    /// This function returns zero on input zero.
-    pub fn invert(&self) -> FieldElement51 {
-        // The bits of p-2 = 2^255 -19 -2 are 11010111111...11.
-        //
-        //                                 nonzero bits of exponent
-        let (t19, t3) = self.pow22501(); // t19: 249..0 ; t3: 3,1,0
-        let t20 = t19.pow2k(5); // 254..5
-        let t21 = &t20 * &t3; // 254..5,3,1,0
-
-        t21
-    }
-
-    /// Compute (self^(2^250-1), self^11), used as a helper function
-    /// within invert() and pow22523().
-    fn pow22501(&self) -> (FieldElement51, FieldElement51) {
-        // Instead of managing which temporary variables are used
-        // for what, we define as many as we need and leave stack
-        // allocation to the compiler
-        //
-        // Each temporary variable t_i is of the form (self)^e_i.
-        // Squaring t_i corresponds to multiplying e_i by 2,
-        // so the pow2k function shifts e_i left by k places.
-        // Multiplying t_i and t_j corresponds to adding e_i + e_j.
-        //
-        // Temporary t_i                      Nonzero bits of e_i
-        //
-        let t0 = self.square(); // 1         e_0 = 2^1
-        let t1 = t0.square().square(); // 3         e_1 = 2^3
-        let t2 = self * &t1; // 3,0       e_2 = 2^3 + 2^0
-        let t3 = &t0 * &t2; // 3,1,0
-        let t4 = t3.square(); // 4,2,1
-        let t5 = &t2 * &t4; // 4,3,2,1,0
-        let t6 = t5.pow2k(5); // 9,8,7,6,5
-        let t7 = &t6 * &t5; // 9,8,7,6,5,4,3,2,1,0
-        let t8 = t7.pow2k(10); // 19..10
-        let t9 = &t8 * &t7; // 19..0
-        let t10 = t9.pow2k(20); // 39..20
-        let t11 = &t10 * &t9; // 39..0
-        let t12 = t11.pow2k(10); // 49..10
-        let t13 = &t12 * &t7; // 49..0
-        let t14 = t13.pow2k(50); // 99..50
-        let t15 = &t14 * &t13; // 99..0
-        let t16 = t15.pow2k(100); // 199..100
-        let t17 = &t16 * &t15; // 199..0
-        let t18 = t17.pow2k(50); // 249..50
-        let t19 = &t18 * &t13; // 249..0
-
-        (t19, t3)
-    }
-
-    /// Load a `FieldElement51` from the low 255 bits of a 256-bit
-    /// input.
-    ///
-    /// # Warning
-    ///
-    /// This function does not check that the input used the canonical
-    /// representative.  It masks the high bit, but it will happily
-    /// decode 2^255 - 18 to 1.  Applications that require a canonical
-    /// encoding of every field element should decode, re-encode to
-    /// the canonical encoding, and check that the input was
-    /// canonical.
-    ///
-    pub fn from_bytes(bytes: &[u8; 32]) -> FieldElement51 {
-        let mut temp = [0u8; 32];
-        temp.copy_from_slice(bytes);
-        temp[31] &= 127u8;
-        let mut output = [0u64; 5];
-        fiat_25519_from_bytes(&mut output, &temp);
-        FieldElement51(output)
-    }
-
-    /// Serialize this `FieldElement51` to a 32-byte array.  The
-    /// encoding is canonical.
-    pub fn to_bytes(&self) -> [u8; 32] {
-        let mut bytes = [0u8; 32];
-        fiat_25519_to_bytes(&mut bytes, &self.0);
-        bytes
-    }
-
-    /// Given `k > 0`, return `self^(2^k)`.
-    pub fn pow2k(&self, mut k: u32) -> FieldElement51 {
-        let mut output = *self;
-        loop {
-            let input = output.0;
-            fiat_25519_carry_square(&mut output.0, &input);
-            k -= 1;
-            if k == 0 {
-                return output;
-            }
-        }
-    }
-
-    /// Given `FieldElements` `u` and `v`, compute either `sqrt(u/v)`
-    /// or `sqrt(i*u/v)` in constant time.
-    ///
-    /// This function always returns the nonnegative square root.
-    ///
-    /// # Return
-    ///
-    /// - `(Choice(1), +sqrt(u/v))  ` if `v` is nonzero and `u/v` is square;
-    /// - `(Choice(1), zero)        ` if `u` is zero;
-    /// - `(Choice(0), zero)        ` if `v` is zero and `u` is nonzero;
-    /// - `(Choice(0), +sqrt(i*u/v))` if `u/v` is nonsquare (so `i*u/v` is square).
-    ///
-    pub fn sqrt_ratio_i(u: &FieldElement51, v: &FieldElement51) -> (Choice, FieldElement51) {
-        // Using the same trick as in ed25519 decoding, we merge the
-        // inversion, the square root, and the square test as follows.
-        //
-        // To compute sqrt(α), we can compute β = α^((p+3)/8).
-        // Then β^2 = ±α, so multiplying β by sqrt(-1) if necessary
-        // gives sqrt(α).
-        //
-        // To compute 1/sqrt(α), we observe that
-        //    1/β = α^(p-1 - (p+3)/8) = α^((7p-11)/8)
-        //                            = α^3 * (α^7)^((p-5)/8).
-        //
-        // We can therefore compute sqrt(u/v) = sqrt(u)/sqrt(v)
-        // by first computing
-        //    r = u^((p+3)/8) v^(p-1-(p+3)/8)
-        //      = u u^((p-5)/8) v^3 (v^7)^((p-5)/8)
-        //      = (uv^3) (uv^7)^((p-5)/8).
-        //
-        // If v is nonzero and u/v is square, then r^2 = ±u/v,
-        //                                     so vr^2 = ±u.
-        // If vr^2 =  u, then sqrt(u/v) = r.
-        // If vr^2 = -u, then sqrt(u/v) = r*sqrt(-1).
-        //
-        // If v is zero, r is also zero.
-
-        let v3 = &v.square() * v;
-        let v7 = &v3.square() * v;
-        let mut r = &(u * &v3) * &(u * &v7).pow_p58();
-        let check = v * &r.square();
-
-        let i = &SQRT_M1;
-
-        let correct_sign_sqrt = check.ct_eq(u);
-        let flipped_sign_sqrt = check.ct_eq(&(-u));
-        let flipped_sign_sqrt_i = check.ct_eq(&(&(-u) * i));
-
-        let r_prime = &SQRT_M1 * &r;
-        r.conditional_assign(&r_prime, flipped_sign_sqrt | flipped_sign_sqrt_i);
-
-        // Choose the nonnegative square root.
-        let r_is_negative = r.is_negative();
-        r.conditional_negate(r_is_negative);
-
-        let was_nonzero_square = correct_sign_sqrt | flipped_sign_sqrt;
-
-        (was_nonzero_square, r)
-    }
-
-    /// Returns the square of this field element.
-    pub fn square(&self) -> FieldElement51 {
-        let mut output = *self;
-        fiat_25519_carry_square(&mut output.0, &self.0);
-        output
-    }
-
-    /// Returns 2 times the square of this field element.
-    pub fn square2(&self) -> FieldElement51 {
-        let mut output = *self;
-        let mut temp = *self;
-        // Void vs return type, measure cost of copying self
-        fiat_25519_carry_square(&mut temp.0, &self.0);
-        fiat_25519_add(&mut output.0, &temp.0, &temp.0);
-        let input = output.0;
-        fiat_25519_carry(&mut output.0, &input);
-        output
-    }
-}
-
-/// Precomputed value of one of the square roots of -1 (mod p)
-pub(crate) const SQRT_M1: FieldElement51 = FieldElement51([
-    1718705420411056,
-    234908883556509,
-    2233514472574048,
-    2117202627021982,
-    765476049583133,
-]);

src/elligator/mod.rs

@@ -1,176 +0,0 @@
-// Copyright (c) Facebook, Inc. and its affiliates.
-//
-// This source code is licensed under the MIT license found in the
-// LICENSE file in the root directory of this source tree.
-#![allow(non_snake_case)]
-
-mod field;
-
-use curve25519_dalek::{edwards::EdwardsPoint, montgomery::MontgomeryPoint};
-use field::FieldElement51;
-use sha2::Digest;
-use subtle::{ConditionallyNegatable, ConditionallySelectable};
-
-const MONT_A: FieldElement51 = FieldElement51([486662, 0, 0, 0, 0]);
-
-fn elligator_signal(r_0: &FieldElement51) -> MontgomeryPoint {
-    let minus_a = -&MONT_A; /* A = 486662 */
-    let one = FieldElement51::one();
-    let d_1 = &one + &r_0.square2(); /* 2r^2 */
-
-    let d = &minus_a * &(d_1.invert()); /* A/(1+2r^2) */
-
-    let d_sq = &d.square();
-    let au = &MONT_A * &d;
-
-    let inner = &(d_sq + &au) + &one;
-    let eps = &d * &inner; /* eps = d^3 + Ad^2 + d */
-
-    let (eps_is_sq, _eps) = FieldElement51::sqrt_ratio_i(&eps, &one);
-
-    let zero = FieldElement51::zero();
-    let Atemp = FieldElement51::conditional_select(&MONT_A, &zero, eps_is_sq); /* 0, or A if nonsquare*/
-    let mut u = &d + &Atemp; /* d, or d+A if nonsquare */
-    u.conditional_negate(!eps_is_sq); /* d, or -d-A if nonsquare */
-
-    MontgomeryPoint(u.to_bytes())
-}
-
-pub fn hash_to_point(bytes: &[u8]) -> EdwardsPoint {
-    let mut hash = sha2::Sha512::new();
-    hash.update(bytes);
-    let h = hash.finalize();
-    let mut res = [0u8; 32];
-    res.copy_from_slice(&h[..32]);
-
-    let sign_bit = (res[31] & 0x80) >> 7;
-
-    let fe = FieldElement51::from_bytes(&res);
-
-    let M1 = elligator_signal(&fe);
-    let E1_opt = M1.to_edwards(sign_bit);
-
-    E1_opt
-        .expect("Montgomery conversion to Edwards point in Elligator failed")
-        .mul_by_cofactor()
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
-    // Signal tests from                                                                                                              //
-    //     https://github.com/signalapp/libsignal-protocol-c/blob/master/src/curve25519/ed25519/tests/internal_fast_tests.c#L222-L282 //
-    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
-
-    const ELLIGATOR_CORRECT_OUTPUT: [u8; 32] = [
-        0x5f, 0x35, 0x20, 0x00, 0x1c, 0x6c, 0x99, 0x36, 0xa3, 0x12, 0x06, 0xaf, 0xe7, 0xc7, 0xac,
-        0x22, 0x4e, 0x88, 0x61, 0x61, 0x9b, 0xf9, 0x88, 0x72, 0x44, 0x49, 0x15, 0x89, 0x9d, 0x95,
-        0xf4, 0x6e,
-    ];
-
-    #[test]
-    fn elligator_correct() {
-        let bytes: Vec<u8> = (0u8..32u8).collect();
-        let mut bits_in = [0u8; 32];
-        bits_in.copy_from_slice(&bytes);
-        let fe = FieldElement51::from_bytes(&bits_in);
-        let eg = elligator_signal(&fe);
-        assert_eq!(eg.to_bytes(), ELLIGATOR_CORRECT_OUTPUT);
-    }
-
-    #[test]
-    fn elligator_zero_zero() {
-        let zero = [0u8; 32];
-        let fe = FieldElement51::from_bytes(&zero);
-        let eg = elligator_signal(&fe);
-        assert_eq!(eg.to_bytes(), zero);
-    }
-
-    const HASHTOPOINT_CORRECT_OUTPUT1: [u8; 32] = [
-        0xce, 0x89, 0x9f, 0xb2, 0x8f, 0xf7, 0x20, 0x91, 0x5e, 0x14, 0xf5, 0xb7, 0x99, 0x08, 0xab,
-        0x17, 0xaa, 0x2e, 0xe2, 0x45, 0xb4, 0xfc, 0x2b, 0xf6, 0x06, 0x36, 0x29, 0x40, 0xed, 0x7d,
-        0xe7, 0xed,
-    ];
-
-    const HASHTOPOINT_CORRECT_OUTPUT2: [u8; 32] = [
-        0xa0, 0x35, 0xbb, 0xa9, 0x4d, 0x30, 0x55, 0x33, 0x0d, 0xce, 0xc2, 0x7f, 0x83, 0xde, 0x79,
-        0xd0, 0x89, 0x67, 0x72, 0x4c, 0x07, 0x8d, 0x68, 0x9d, 0x61, 0x52, 0x1d, 0xf9, 0x2c, 0x5c,
-        0xba, 0x77,
-    ];
-
-    #[test]
-    fn test_hash_to_point_1() {
-        let bits: Vec<u8> = (0u8..32u8).collect();
-        let hashed = hash_to_point(&bits);
-        assert_eq!(hashed.compress().to_bytes(), HASHTOPOINT_CORRECT_OUTPUT1);
-    }
-
-    #[test]
-    fn test_hash_to_point_2() {
-        let bits: Vec<u8> = (0u8..32u8).map(|u| u + 1).collect();
-        let hashed = hash_to_point(&bits);
-        assert_eq!(hashed.compress().to_bytes(), HASHTOPOINT_CORRECT_OUTPUT2);
-    }
-
-    /////////////////////////////////////////
-    // Additional test vectors from Signal //
-    /////////////////////////////////////////
-
-    fn test_vectors() -> Vec<Vec<&'static str>> {
-        vec![
-            vec![
-                "214f306e1576f5a7577636fe303ca2c625b533319f52442b22a9fa3b7ede809f",
-                "c95becf0f93595174633b9d4d6bbbeb88e16fa257176f877ce426e1424626052",
-            ],
-            vec![
-                "2eb10d432702ea7f79207da95d206f82d5a3b374f5f89f17a199531f78d3bea6",
-                "d8f8b508edffbb8b6dab0f602f86a9dd759f800fe18f782fdcac47c234883e7f",
-            ],
-            vec![
-                "84cbe9accdd32b46f4a8ef51c85fd39d028711f77fb00e204a613fc235fd68b9",
-                "93c73e0289afd1d1fc9e4e78a505d5d1b2642fbdf91a1eff7d281930654b1453",
-            ],
-            vec![
-                "c85165952490dc1839cb69012a3d9f2cc4b02343613263ab93a26dc89fd58267",
-                "43cbe8685fd3c90665b91835debb89ff1477f906f5170f38a192f6a199556537",
-            ],
-            vec![
-                "26e7fc4a78d863b1a4ccb2ce0951fbcd021e106350730ee4157bacb4502e1b76",
-                "b6fc3d738c2c40719479b2f23818180cdafa72a14254d4016bbed8f0b788a835",
-            ],
-            vec![
-                "1618c08ef0233f94f0f163f9435ec7457cd7a8cd4bb6b160315d15818c30f7a2",
-                "da0b703593b29dbcd28ebd6e7baea17b6f61971f3641cae774f6a5137a12294c",
-            ],
-            vec![
-                "48b73039db6fcdcb6030c4a38e8be80b6390d8ae46890e77e623f87254ef149c",
-                "ca11b25acbc80566603eabeb9364ebd50e0306424c61049e1ce9385d9f349966",
-            ],
-            vec![
-                "a744d582b3a34d14d311b7629da06d003045ae77cebceeb4e0e72734d63bd07d",
-                "fad25a5ea15d4541258af8785acaf697a886c1b872c793790e60a6837b1adbc0",
-            ],
-            vec![
-                "80a6ff33494c471c5eff7efb9febfbcf30a946fe6535b3451cda79f2154a7095",
-                "57ac03913309b3f8cd3c3d4c49d878bb21f4d97dc74a1eaccbe5c601f7f06f47",
-            ],
-            vec![
-                "f06fc939bc10551a0fd415aebf107ef0b9c4ee1ef9a164157bdd089127782617",
-                "785b2a6a00a5579cc9da1ff997ce8339b6f9fb46c6f10cf7a12ff2986341a6e0",
-            ],
-        ]
-    }
-
-    #[test]
-    fn additional_signal_test_vectors() {
-        for vector in test_vectors().iter() {
-            let input = hex::decode(vector[0]).unwrap();
-            let output = hex::decode(vector[1]).unwrap();
-
-            let point = hash_to_point(&input);
-            assert_eq!(point.compress().to_bytes(), output[..]);
-        }
-    }
-}

src/envelope.rs

@@ -3,26 +3,83 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the root directory of this source tree.
 
-use crate::errors::InternalPakeError;
-use crate::hash::Hash;
-use digest::Digest;
-use generic_array::{
-    typenum::{Unsigned, U32},
-    GenericArray,
+use crate::{
+    errors::{utils::check_slice_size_atleast, InternalPakeError, PakeError, ProtocolError},
+    hash::Hash,
+    keypair::Key,
+    serialization::serialize,
 };
+use digest::Digest;
+use generic_array::{typenum::Unsigned, GenericArray};
+use generic_bytes::SizedBytes;
 use hkdf::Hkdf;
 use hmac::{Hmac, Mac, NewMac};
-use rand_core::{CryptoRng, RngCore};
+use rand::{CryptoRng, RngCore};
+use std::convert::TryFrom;
 
 // Constant string used as salt for HKDF computation
-const STR_ENVU: &[u8] = b"EnvU";
-
-/// The length of the "export key" output by the client registration
-/// and login finish steps
-pub(crate) type ExportKeySize = U32;
+const STR_PAD: &[u8] = b"Pad";
+const STR_AUTH_KEY: &[u8] = b"AuthKey";
+const STR_EXPORT_KEY: &[u8] = b"ExportKey";
 
 const NONCE_LEN: usize = 32;
 
+#[derive(Clone, Copy, PartialEq)]
+pub(crate) enum InnerEnvelopeMode {
+    Base = 1,
+    CustomIdentifier = 2,
+}
+
+impl TryFrom<u8> for InnerEnvelopeMode {
+    type Error = PakeError;
+    fn try_from(x: u8) -> Result<Self, Self::Error> {
+        match x {
+            1 => Ok(InnerEnvelopeMode::Base),
+            2 => Ok(InnerEnvelopeMode::CustomIdentifier),
+            _ => Err(PakeError::SerializationError),
+        }
+    }
+}
+
+pub(crate) struct InnerEnvelope {
+    mode: InnerEnvelopeMode,
+    nonce: Vec<u8>,
+    ciphertext: Vec<u8>,
+}
+
+impl InnerEnvelope {
+    pub(crate) fn serialize(&self) -> Vec<u8> {
+        [&[self.mode as u8], &self.nonce[..], &self.ciphertext[..]].concat()
+    }
+
+    pub(crate) fn deserialize(input: &[u8]) -> Result<(Self, Vec<u8>), ProtocolError> {
+        if input.is_empty() {
+            return Err(ProtocolError::VerificationError(
+                PakeError::SerializationError,
+            ));
+        }
+        let mode = InnerEnvelopeMode::try_from(input[0])?;
+
+        let key_len = <Key as SizedBytes>::Len::to_usize();
+
+        let bytes = &input[1..];
+        if bytes.len() < NONCE_LEN + key_len {
+            return Err(ProtocolError::VerificationError(
+                PakeError::SerializationError,
+            ));
+        }
+
+        Ok((
+            Self {
+                mode,
+                nonce: bytes[..NONCE_LEN].to_vec(),
+                ciphertext: bytes[NONCE_LEN..NONCE_LEN + key_len].to_vec(),
+            },
+            bytes[NONCE_LEN + key_len..].to_vec(),
+        ))
+    }
+}
+
 /// This struct is an instantiation of the envelope as described in
 /// https://tools.ietf.org/html/draft-krawczyk-cfrg-opaque-06#section-4
 ///
@@ -34,82 +91,106 @@ const NONCE_LEN: usize = 32;
 /// an XOR-based approach without compromising on security, and to avoid
 /// the confusion around the implementation of an RKR-secure encryption.
 pub(crate) struct Envelope<D: Hash> {
-    nonce: Vec<u8>,
-    ciphertext: Vec<u8>,
+    inner_envelope: InnerEnvelope,
     hmac: GenericArray<u8, <D as Digest>::OutputSize>,
 }
 
-pub(crate) struct OpenedEnvelope {
+// Note that this struct represents an envelope that has been "opened" with the asssociated
+// key. This key is also used to derive the export_key parameter, which is technically
+// unrelated to the envelope's encrypted and authenticated contents.
+pub(crate) struct OpenedEnvelope<D: Hash> {
+    pub(crate) client_s_sk: Vec<u8>,
+    pub(crate) export_key: GenericArray<u8, <D as Digest>::OutputSize>,
+}
+
+pub(crate) struct OpenedInnerEnvelope<D: Hash> {
     pub(crate) plaintext: Vec<u8>,
-    pub(crate) export_key: GenericArray<u8, ExportKeySize>,
+    pub(crate) export_key: GenericArray<u8, <D as Digest>::OutputSize>,
 }
 
 impl<D: Hash> Envelope<D> {
-    /// The additional number of bytes added to the plaintext
-    pub(crate) fn additional_size() -> usize {
-        NONCE_LEN + <D as Digest>::OutputSize::to_usize()
-    }
-
     fn hmac_key_size() -> usize {
         <D as Digest>::OutputSize::to_usize()
     }
 
-    fn hmac_size() -> usize {
+    fn export_key_size() -> usize {
         <D as Digest>::OutputSize::to_usize()
     }
 
-    fn export_key_size() -> usize {
-        ExportKeySize::to_usize()
-    }
-
-    pub(crate) fn new(
-        nonce: Vec<u8>,
-        ciphertext: Vec<u8>,
-        hmac: GenericArray<u8, <D as Digest>::OutputSize>,
-    ) -> Self {
-        Self {
-            nonce,
-            ciphertext,
-            hmac,
-        }
+    pub(crate) fn get_mode(&self) -> InnerEnvelopeMode {
+        self.inner_envelope.mode
     }
 
     /// The format of the output is:
-    /// nonce             | ciphertext       | hmac
-    /// nonce_size bytes  | variable length  | hmac_size bytes
+    /// mode | nonce             | ciphertext       | hmac
+    /// u8   | nonce_size bytes  | variable length  | hmac_size bytes
     pub(crate) fn from_bytes(bytes: &[u8]) -> Result<Self, InternalPakeError> {
-        let ciphertext_start = NONCE_LEN;
-        let ciphertext_end = bytes.len() - Self::hmac_size();
-
-        Ok(Self::new(
-            bytes[..ciphertext_start].to_vec(),
-            bytes[ciphertext_start..ciphertext_end].to_vec(),
-            GenericArray::clone_from_slice(&bytes[ciphertext_end..]),
-        ))
+        let (result, remainder) = Self::deserialize(bytes)
+            .map_err(|_| InternalPakeError::InvalidEnvelopeStructureError)?;
+        if !remainder.is_empty() {
+            return Err(InternalPakeError::InvalidEnvelopeStructureError);
+        }
+        Ok(result)
     }
 
     pub(crate) fn to_bytes(&self) -> Vec<u8> {
-        [&self.nonce[..], &self.ciphertext[..], &self.hmac[..]].concat()
+        self.serialize()
+    }
+
+    pub(crate) fn serialize(&self) -> Vec<u8> {
+        [&self.inner_envelope.serialize(), &self.hmac[..]].concat()
+    }
+
+    pub(crate) fn deserialize(input: &[u8]) -> Result<(Self, Vec<u8>), ProtocolError> {
+        let (inner_envelope, remainder) = InnerEnvelope::deserialize(input)?;
+
+        let hmac_key_size = Self::hmac_key_size();
+        let hmac_and_remainder =
+            check_slice_size_atleast(&remainder, hmac_key_size, "hmac_key_size")?;
+
+        Ok((
+            Self {
+                inner_envelope,
+                hmac: GenericArray::clone_from_slice(&hmac_and_remainder[..hmac_key_size]),
+            },
+            hmac_and_remainder[hmac_key_size..].to_vec(),
+        ))
+    }
+
+    pub(crate) fn seal<R: RngCore + CryptoRng>(
+        rng: &mut R,
+        key: &[u8],
+        client_s_sk: &[u8],
+        server_s_pk: &[u8],
+        optional_ids: Option<(Vec<u8>, Vec<u8>)>,
+    ) -> Result<(Self, GenericArray<u8, <D as Digest>::OutputSize>), InternalPakeError> {
+        let aad = construct_aad(server_s_pk, &optional_ids);
+        Self::seal_raw(rng, key, &client_s_sk, &aad, mode_from_ids(&optional_ids))
     }
 
     /// Uses a key to convert the plaintext into an envelope, authenticated by the aad field.
     /// Note that a new nonce is sampled for each call to seal.
-    pub(crate) fn seal<R: RngCore + CryptoRng>(
+    pub(crate) fn seal_raw<R: RngCore + CryptoRng>(
+        rng: &mut R,
         key: &[u8],
         plaintext: &[u8],
         aad: &[u8],
-        rng: &mut R,
-    ) -> Result<(Self, GenericArray<u8, ExportKeySize>), InternalPakeError> {
+        mode: InnerEnvelopeMode,
+    ) -> Result<(Self, GenericArray<u8, <D as Digest>::OutputSize>), InternalPakeError> {
         let mut nonce = vec![0u8; NONCE_LEN];
         rng.fill_bytes(&mut nonce);
 
         let h = Hkdf::<D>::new(Some(&nonce), &key);
-        let mut okm = vec![0u8; plaintext.len() + Self::hmac_key_size() + Self::export_key_size()];
-        h.expand(STR_ENVU, &mut okm)
+        let mut xor_key = vec![0u8; plaintext.len()];
+        let mut hmac_key = vec![0u8; Self::hmac_key_size()];
+        let mut export_key = vec![0u8; Self::export_key_size()];
+
+        h.expand(STR_PAD, &mut xor_key)
+            .map_err(|_| InternalPakeError::HkdfError)?;
+        h.expand(STR_AUTH_KEY, &mut hmac_key)
+            .map_err(|_| InternalPakeError::HkdfError)?;
+        h.expand(STR_EXPORT_KEY, &mut export_key)
             .map_err(|_| InternalPakeError::HkdfError)?;
-        let xor_key = &okm[..plaintext.len()];
-        let hmac_key = &okm[plaintext.len()..plaintext.len() + Self::hmac_key_size()];
-        let export_key = &okm[plaintext.len() + Self::hmac_key_size()..];
 
         let ciphertext: Vec<u8> = xor_key
             .iter()
@@ -117,34 +198,75 @@ impl<D: Hash> Envelope<D> {
             .map(|(&x1, &x2)| x1 ^ x2)
             .collect();
 
+        let inner_envelope = InnerEnvelope {
+            mode,
+            nonce,
+            ciphertext,
+        };
+
         let mut hmac =
             Hmac::<D>::new_varkey(&hmac_key).map_err(|_| InternalPakeError::HmacError)?;
-        hmac.update(&nonce);
-        hmac.update(&ciphertext);
+        hmac.update(&inner_envelope.serialize());
         hmac.update(&aad);
 
+        let hmac_bytes = hmac.finalize().into_bytes();
+
         Ok((
-            Self::new(nonce, ciphertext.to_vec(), hmac.finalize().into_bytes()),
-            *GenericArray::from_slice(&export_key),
+            Self {
+                inner_envelope,
+                hmac: hmac_bytes,
+            },
+            GenericArray::clone_from_slice(&export_key),
         ))
     }
 
+    pub(crate) fn open(
+        &self,
+        key: &[u8],
+        server_s_pk: &[u8],
+        optional_ids: &Option<(Vec<u8>, Vec<u8>)>,
+    ) -> Result<OpenedEnvelope<D>, InternalPakeError> {
+        // First, check that mode matches
+        if self.inner_envelope.mode != mode_from_ids(optional_ids) {
+            return Err(InternalPakeError::IncompatibleEnvelopeModeError);
+        }
+
+        let aad = construct_aad(server_s_pk, optional_ids);
+        let opened = self.open_raw(key, &aad)?;
+
+        if opened.plaintext.len() != <Key as SizedBytes>::Len::to_usize() {
+            // Plaintext should consist of a single key
+            return Err(InternalPakeError::UnexpectedEnvelopeContentsError);
+        }
+
+        Ok(OpenedEnvelope {
+            client_s_sk: opened.plaintext,
+            export_key: opened.export_key,
+        })
+    }
+
     /// Attempts to decrypt the envelope using a key, which is successful only if the key and
     /// aad used to construct the envelope are the same.
-    pub(crate) fn open(&self, key: &[u8], aad: &[u8]) -> Result<OpenedEnvelope, InternalPakeError> {
-        let h = Hkdf::<D>::new(Some(&self.nonce), &key);
-        let mut okm =
-            vec![0u8; self.ciphertext.len() + Self::hmac_key_size() + Self::export_key_size()];
-        h.expand(STR_ENVU, &mut okm)
+    pub(crate) fn open_raw(
+        &self,
+        key: &[u8],
+        aad: &[u8],
+    ) -> Result<OpenedInnerEnvelope<D>, InternalPakeError> {
+        let h = Hkdf::<D>::new(Some(&self.inner_envelope.nonce), &key);
+        let mut xor_key = vec![0u8; self.inner_envelope.ciphertext.len()];
+        let mut hmac_key = vec![0u8; Self::hmac_key_size()];
+        let mut export_key = vec![0u8; Self::export_key_size()];
+
+        h.expand(STR_PAD, &mut xor_key)
+            .map_err(|_| InternalPakeError::HkdfError)?;
+        h.expand(STR_AUTH_KEY, &mut hmac_key)
+            .map_err(|_| InternalPakeError::HkdfError)?;
+        h.expand(STR_EXPORT_KEY, &mut export_key)
             .map_err(|_| InternalPakeError::HkdfError)?;
-        let xor_key = &okm[..self.ciphertext.len()];
-        let hmac_key = &okm[self.ciphertext.len()..self.ciphertext.len() + Self::hmac_key_size()];
-        let export_key = &okm[self.ciphertext.len() + Self::hmac_key_size()..];
 
         let mut hmac =
             Hmac::<D>::new_varkey(&hmac_key).map_err(|_| InternalPakeError::HmacError)?;
-        hmac.update(&self.nonce);
-        hmac.update(&self.ciphertext);
+        hmac.update(&self.inner_envelope.serialize());
         hmac.update(aad);
         if hmac.verify(&self.hmac).is_err() {
             return Err(InternalPakeError::SealOpenHmacError);
@@ -152,20 +274,39 @@ impl<D: Hash> Envelope<D> {
 
         let plaintext: Vec<u8> = xor_key
             .iter()
-            .zip(self.ciphertext.iter())
+            .zip(self.inner_envelope.ciphertext.iter())
             .map(|(&x1, &x2)| x1 ^ x2)
             .collect();
-        Ok(OpenedEnvelope {
+        Ok(OpenedInnerEnvelope {
             plaintext,
-            export_key: *GenericArray::from_slice(&export_key),
+            export_key: GenericArray::<u8, <D as Digest>::OutputSize>::clone_from_slice(
+                &export_key,
+            ),
         })
     }
 }
 
+// Helper functions
+
+fn construct_aad(server_s_pk: &[u8], optional_ids: &Option<(Vec<u8>, Vec<u8>)>) -> Vec<u8> {
+    let ids = optional_ids
+        .iter()
+        .flat_map(|(l, r)| [serialize(l, 2), serialize(r, 2)].concat())
+        .collect();
+    [server_s_pk.to_vec(), ids].concat()
+}
+
+pub(crate) fn mode_from_ids(optional_ids: &Option<(Vec<u8>, Vec<u8>)>) -> InnerEnvelopeMode {
+    match optional_ids {
+        Some(_) => InnerEnvelopeMode::CustomIdentifier,
+        None => InnerEnvelopeMode::Base,
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
-    use rand_core::OsRng;
+    use rand::rngs::OsRng;
 
     #[test]
     fn seal_and_open() {
@@ -176,9 +317,15 @@ mod tests {
         let mut msg = [0u8; 100];
         rng.fill_bytes(&mut msg);
 
-        let (envelope, export_key_1) =
-            Envelope::<sha2::Sha256>::seal(&key, &msg, b"aad", &mut rng).unwrap();
-        let opened_envelope = envelope.open(&key, b"aad").unwrap();
+        let (envelope, export_key_1) = Envelope::<sha2::Sha256>::seal_raw(
+            &mut rng,
+            &key,
+            &msg,
+            b"aad",
+            InnerEnvelopeMode::Base,
+        )
+        .unwrap();
+        let opened_envelope = envelope.open_raw(&key, b"aad").unwrap();
         assert_eq!(&msg.to_vec(), &opened_envelope.plaintext);
         assert_eq!(&export_key_1.to_vec(), &opened_envelope.export_key.to_vec());
     }

src/errors.rs

@@ -10,6 +10,8 @@ use thiserror::Error;
 /// Represents an error in the manipulation of internal cryptographic data
 #[derive(Debug, Display, Error)]
 pub enum InternalPakeError {
+    /// Deserializing from a byte sequence failed
+    InvalidByteSequence,
     /// Invalid length for {name}: expected {len}, but is actually {actual_len}.
     SizeError {
         /// name
@@ -25,6 +27,8 @@ pub enum InternalPakeError {
     SubGroupError,
     /// hashing to a key failed
     HashingFailure,
+    /// Computing the hash-to-curve function failed
+    HashToCurveError,
     /// Computing HKDF failed while deriving subkeys
     HkdfError,
     /// Computing HMAC failed while supplying a secret key
@@ -40,6 +44,15 @@ pub enum InternalPakeError {
     /// This error occurs when the envelope seal open hmac check fails
     /// HMAC check in seal open failed.
     SealOpenHmacError,
+    /// This error occurs when the envelope cannot be constructed properly
+    /// based on the credentials that were specified to be required.
+    InvalidEnvelopeStructureError,
+    /// This error occurs when attempting to open an envelope of the wrong
+    /// type (base mode, custom identifier)
+    IncompatibleEnvelopeModeError,
+    /// This error occurs when the envelope is opened and deserialization
+    /// fails
+    UnexpectedEnvelopeContentsError,
 }
 
 /// Represents an error in password checking
@@ -58,6 +71,8 @@ pub enum PakeError {
     KeyExchangeMacValidationError,
     /// Error in validating credentials
     InvalidLoginError,
+    /// Error with serializing / deserializing protocol messages
+    SerializationError,
 }
 
 // This is meant to express future(ly) non-trivial ways of converting the
@@ -78,6 +93,9 @@ pub enum ProtocolError {
     /// This error occurs when the server answer cannot be handled
     /// Server response cannot be handled.
     ServerError,
+    /// This error occurs when the server specifies an envelope credentials
+    /// format that is invalid
+    ServerInvalidEnvelopeCredentialsFormatError,
     /// This error occurs when the client request cannot be handled
     /// Client request cannot be handled.
     ClientError,
@@ -108,6 +126,24 @@ impl From<::std::convert::Infallible> for ProtocolError {
     }
 }
 
+impl From<generic_bytes::TryFromSizedBytesError> for InternalPakeError {
+    fn from(_: generic_bytes::TryFromSizedBytesError) -> Self {
+        InternalPakeError::InvalidByteSequence
+    }
+}
+
+impl From<generic_bytes::TryFromSizedBytesError> for PakeError {
+    fn from(e: generic_bytes::TryFromSizedBytesError) -> Self {
+        PakeError::CryptoError(e.into())
+    }
+}
+
+impl From<generic_bytes::TryFromSizedBytesError> for ProtocolError {
+    fn from(e: generic_bytes::TryFromSizedBytesError) -> Self {
+        PakeError::CryptoError(e.into()).into()
+    }
+}
+
 pub(crate) mod utils {
     use super::*;
 
@@ -125,4 +161,19 @@ pub(crate) mod utils {
         }
         Ok(slice)
     }
+
+    pub fn check_slice_size_atleast<'a>(
+        slice: &'a [u8],
+        expected_len: usize,
+        arg_name: &'static str,
+    ) -> Result<&'a [u8], InternalPakeError> {
+        if slice.len() < expected_len {
+            return Err(InternalPakeError::SizeError {
+                name: arg_name,
+                len: expected_len,
+                actual_len: slice.len(),
+            });
+        }
+        Ok(slice)
+    }
 }

src/group.rs

@@ -6,11 +6,10 @@
 //! Defines the Group trait to specify the underlying prime order group used in
 //! OPAQUE's OPRF
 
-use crate::elligator;
 use crate::errors::InternalPakeError;
 
 use curve25519_dalek::{
-    edwards::{CompressedEdwardsY, EdwardsPoint},
+    constants::RISTRETTO_BASEPOINT_POINT,
     ristretto::{CompressedRistretto, RistrettoPoint},
     scalar::Scalar,
 };
@@ -18,18 +17,20 @@ use generic_array::{
     typenum::{U32, U64},
     ArrayLength, GenericArray,
 };
-use rand_core::{CryptoRng, RngCore};
+use std::convert::TryInto;
+
+use rand::{CryptoRng, RngCore};
 use std::ops::Mul;
 use zeroize::Zeroize;
 
 /// A prime-order subgroup of a base field (EC, prime-order field ...). This
 /// subgroup is noted additively — as in the draft RFC — in this trait.
-pub trait Group: Sized + for<'a> Mul<&'a <Self as Group>::Scalar, Output = Self> {
+pub trait Group: Copy + Sized + for<'a> Mul<&'a <Self as Group>::Scalar, Output = Self> {
     /// The type of base field scalars
-    type Scalar: Zeroize;
+    type Scalar: Zeroize + Clone;
     /// The byte length necessary to represent scalars
     type ScalarLen: ArrayLength<u8>;
-    /// Return a scalat from its fixed-length bytes representation
+    /// Return a scalar from its fixed-length bytes representation
     fn from_scalar_slice(
         scalar_bits: &GenericArray<u8, Self::ScalarLen>,
     ) -> Result<Self::Scalar, InternalPakeError>;
@@ -57,6 +58,12 @@ pub trait Group: Sized + for<'a> Mul<&'a <Self as Group>::Scalar, Output = Self>
 
     /// Hashes a slice of pseudo-random bytes of the correct length to a curve point
     fn hash_to_curve(uniform_bytes: &GenericArray<u8, Self::UniformBytesLen>) -> Self;
+
+    /// Get the base point for the group
+    fn base_point() -> Self;
+
+    /// Multiply the point by a scalar, represented as a slice
+    fn mult_by_slice(&self, scalar: &GenericArray<u8, Self::ScalarLen>) -> Self;
 }
 
 /// The implementation of such a subgroup for Ristretto
@@ -71,7 +78,20 @@ impl Group for RistrettoPoint {
         Ok(Scalar::from_bytes_mod_order(bits))
     }
     fn random_scalar<R: RngCore + CryptoRng>(rng: &mut R) -> Self::Scalar {
-        Scalar::random(rng)
+        #[cfg(not(test))]
+        {
+            let mut scalar_bytes = [0u8; 64];
+            rng.fill_bytes(&mut scalar_bytes);
+            Scalar::from_bytes_mod_order_wide(&scalar_bytes)
+        }
+
+        // Tests need an exact conversion from bytes to scalar, sampling only 32 bytes from rng
+        #[cfg(test)]
+        {
+            let mut scalar_bytes = [0u8; 32];
+            rng.fill_bytes(&mut scalar_bytes);
+            Scalar::from_bytes_mod_order(scalar_bytes)
+        }
     }
     fn scalar_as_bytes(scalar: &Self::Scalar) -> &GenericArray<u8, Self::ScalarLen> {
         GenericArray::from_slice(scalar.as_bytes())
@@ -87,7 +107,7 @@ impl Group for RistrettoPoint {
     ) -> Result<Self, InternalPakeError> {
         CompressedRistretto::from_slice(element_bits)
             .decompress()
-            .ok_or_else(|| InternalPakeError::PointError)
+            .ok_or(InternalPakeError::PointError)
     }
     // serialization of a group element
     fn to_arr(&self) -> GenericArray<u8, Self::ElemLen> {
@@ -97,114 +117,21 @@ impl Group for RistrettoPoint {
 
     type UniformBytesLen = U64;
     fn hash_to_curve(uniform_bytes: &GenericArray<u8, Self::UniformBytesLen>) -> Self {
-        let mut bits = [0u8; 64];
-        bits.copy_from_slice(&uniform_bytes);
-
+        // https://caniuse.rs/features/array_gt_32_impls
+        let bits: [u8; 64] = {
+            let mut bytes = [0u8; 64];
+            bytes.copy_from_slice(uniform_bytes);
+            bytes
+        };
         RistrettoPoint::from_uniform_bytes(&bits)
     }
-}
 
-/// The implementation of such a subgroup for points on the large Curve25519-subgroup
-impl Group for EdwardsPoint {
-    type Scalar = Scalar;
-    type ScalarLen = U32;
-    fn from_scalar_slice(
-        scalar_bits: &GenericArray<u8, Self::ScalarLen>,
-    ) -> Result<Self::Scalar, InternalPakeError> {
-        let mut bits = [0u8; 32];
-        bits.copy_from_slice(scalar_bits);
-        Ok(Scalar::from_bytes_mod_order(bits))
-    }
-    fn random_scalar<R: RngCore + CryptoRng>(rng: &mut R) -> Self::Scalar {
-        Scalar::random(rng)
-    }
-    fn scalar_as_bytes(scalar: &Self::Scalar) -> &GenericArray<u8, Self::ScalarLen> {
-        GenericArray::from_slice(scalar.as_bytes())
-    }
-    fn scalar_invert(scalar: &Self::Scalar) -> Self::Scalar {
-        scalar.invert()
+    fn base_point() -> Self {
+        RISTRETTO_BASEPOINT_POINT
     }
 
-    // The byte length necessary to represent group elements
-    type ElemLen = U32;
-    fn from_element_slice(
-        element_bits: &GenericArray<u8, Self::ElemLen>,
-    ) -> Result<Self, InternalPakeError> {
-        let point = CompressedEdwardsY::from_slice(element_bits)
-            .decompress()
-            .ok_or_else(|| InternalPakeError::PointError)?;
-
-        if point.is_small_order() {
-            return Err(InternalPakeError::SubGroupError);
-        }
-        Ok(point)
-    }
-    // serialization of a group element
-    fn to_arr(&self) -> GenericArray<u8, Self::ElemLen> {
-        let c = self.compress();
-        *GenericArray::from_slice(c.as_bytes())
-    }
-
-    type UniformBytesLen = U32;
-    fn hash_to_curve(uniform_bytes: &GenericArray<u8, Self::UniformBytesLen>) -> Self {
-        elligator::hash_to_point(uniform_bytes)
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use anyhow::{anyhow, Result};
-
-    const EIGHT_TORSION: [[u8; 32]; 8] = [
-        [
-            1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0,
-        ],
-        [
-            199, 23, 106, 112, 61, 77, 216, 79, 186, 60, 11, 118, 13, 16, 103, 15, 42, 32, 83, 250,
-            44, 57, 204, 198, 78, 199, 253, 119, 146, 172, 3, 122,
-        ],
-        [
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 128,
-        ],
-        [
-            38, 232, 149, 143, 194, 178, 39, 176, 69, 195, 244, 137, 242, 239, 152, 240, 213, 223,
-            172, 5, 211, 198, 51, 57, 177, 56, 2, 136, 109, 83, 252, 5,
-        ],
-        [
-            236, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-            255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 127,
-        ],
-        [
-            38, 232, 149, 143, 194, 178, 39, 176, 69, 195, 244, 137, 242, 239, 152, 240, 213, 223,
-            172, 5, 211, 198, 51, 57, 177, 56, 2, 136, 109, 83, 252, 133,
-        ],
-        [
-            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-            0, 0, 0,
-        ],
-        [
-            199, 23, 106, 112, 61, 77, 216, 79, 186, 60, 11, 118, 13, 16, 103, 15, 42, 32, 83, 250,
-            44, 57, 204, 198, 78, 199, 253, 119, 146, 172, 3, 250,
-        ],
-    ];
-
-    fn deserialize_point(pt: &[u8]) -> Result<EdwardsPoint> {
-        let mut bytes = [0u8; 32];
-        bytes.copy_from_slice(&pt[..32]);
-
-        curve25519_dalek::edwards::CompressedEdwardsY(bytes)
-            .decompress()
-            .ok_or_else(|| anyhow!("Point decompression failed!"))
-    }
-
-    #[test]
-    fn test_small_subgroup_edwards() {
-        for pt in &EIGHT_TORSION[..] {
-            assert!(deserialize_point(&pt[..]).is_ok());
-            assert!(EdwardsPoint::from_element_slice(GenericArray::from_slice(&pt[..])).is_err());
-        }
+    fn mult_by_slice(&self, scalar: &GenericArray<u8, Self::ScalarLen>) -> Self {
+        let arr: [u8; 32] = scalar.as_slice().try_into().expect("Wrong length");
+        self * Scalar::from_bits(arr)
     }
 }

src/hash.rs

@@ -3,20 +3,13 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the root directory of this source tree.
 
+//! A convenience trait for digest bounds used throughout the library
+
 use digest::{BlockInput, FixedOutput, Reset, Update};
-use generic_array::ArrayLength;
 
 /// Trait inheriting the requirements from digest::Digest for compatibility with HKDF and HMAC
 // Associated types could be simplified when they are made as defaults:
 // https://github.com/rust-lang/rust/issues/29661
-pub trait Hash: Update + BlockInput + FixedOutput + Reset + Default + Clone {
-    /// The block size for the hash function
-    type BlockSize: ArrayLength<u8>;
-    /// The output size of the hash function
-    type OutputSize: ArrayLength<u8>;
-}
+pub trait Hash: Update + BlockInput + FixedOutput + Reset + Default + Clone {}
 
-impl<T: Update + BlockInput + FixedOutput + Reset + Default + Clone> Hash for T {
-    type BlockSize = T::BlockSize;
-    type OutputSize = T::OutputSize;
-}
+impl<T: Update + BlockInput + FixedOutput + Reset + Default + Clone> Hash for T {}

src/key_exchange/traits.rs

@@ -4,50 +4,58 @@
 // LICENSE file in the root directory of this source tree.
 
 use crate::{
-    errors::{InternalPakeError, ProtocolError},
+    errors::{PakeError, ProtocolError},
+    group::Group,
     hash::Hash,
-    keypair::{Key, KeyPair},
+    keypair::Key,
 };
-use rand_core::{CryptoRng, RngCore};
+use rand::{CryptoRng, RngCore};
 
 use std::convert::TryFrom;
 
-pub trait KeyExchange<D: Hash> {
-    type KE1State: TryFrom<Vec<u8>, Error = InternalPakeError> + ToBytes;
-    type KE2State: TryFrom<Vec<u8>, Error = ProtocolError> + ToBytes;
-    type KE1Message: TryFrom<Vec<u8>, Error = InternalPakeError> + ToBytes;
-    type KE2Message: TryFrom<Vec<u8>, Error = ProtocolError> + ToBytes;
-    type KE3Message: TryFrom<Vec<u8>, Error = ProtocolError> + ToBytes;
+pub trait KeyExchange<D: Hash, G: Group> {
+    type KE1State: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytes;
+    type KE2State: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytes;
+    type KE1Message: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytes;
+    type KE2Message: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytes;
+    type KE3Message: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytes;
 
-    fn generate_ke1<R: RngCore + CryptoRng, KeyFormat: KeyPair<Repr = Key>>(
-        l1_component: Vec<u8>,
+    fn generate_ke1<R: RngCore + CryptoRng>(
+        info: Vec<u8>,
         rng: &mut R,
     ) -> Result<(Self::KE1State, Self::KE1Message), ProtocolError>;
 
-    fn generate_ke2<R: RngCore + CryptoRng, KeyFormat: KeyPair<Repr = Key>>(
+    #[allow(clippy::too_many_arguments, clippy::type_complexity)]
+    fn generate_ke2<R: RngCore + CryptoRng>(
         rng: &mut R,
         l1_bytes: Vec<u8>,
         l2_bytes: Vec<u8>,
         ke1_message: Self::KE1Message,
-        client_s_pk: KeyFormat::Repr,
-        server_s_sk: KeyFormat::Repr,
-    ) -> Result<(Self::KE2State, Self::KE2Message), ProtocolError>;
+        client_s_pk: Key,
+        server_s_sk: Key,
+        id_u: Vec<u8>,
+        id_s: Vec<u8>,
+        e_info: Vec<u8>,
+    ) -> Result<(Vec<u8>, Self::KE2State, Self::KE2Message), ProtocolError>;
 
-    fn generate_ke3<KeyFormat: KeyPair<Repr = Key>>(
+    #[allow(clippy::too_many_arguments, clippy::type_complexity)]
+    fn generate_ke3(
         l2_component: Vec<u8>,
         ke2_message: Self::KE2Message,
         ke1_state: &Self::KE1State,
-        server_s_pk: KeyFormat::Repr,
-        client_s_sk: KeyFormat::Repr,
-    ) -> Result<(Vec<u8>, Self::KE3Message), ProtocolError>;
+        serialized_credential_request: &[u8],
+        server_s_pk: Key,
+        client_s_sk: Key,
+        id_u: Vec<u8>,
+        id_s: Vec<u8>,
+    ) -> Result<(Vec<u8>, Vec<u8>, Self::KE3Message), ProtocolError>;
 
+    #[allow(clippy::type_complexity)]
     fn finish_ke(
         ke3_message: Self::KE3Message,
         ke2_state: &Self::KE2State,
     ) -> Result<Vec<u8>, ProtocolError>;
 
-    fn ke1_state_size() -> usize;
-
     fn ke2_message_size() -> usize;
 }
 

src/key_exchange/tripledh.rs

@@ -5,184 +5,215 @@
 
 //! An implementation of the Triple Diffie-Hellman key exchange protocol
 use crate::{
-    errors::{utils::check_slice_size, InternalPakeError, PakeError, ProtocolError},
+    errors::{
+        utils::{check_slice_size, check_slice_size_atleast},
+        InternalPakeError, PakeError, ProtocolError,
+    },
+    group::Group,
     hash::Hash,
     key_exchange::traits::{KeyExchange, ToBytes},
-    keypair::{Key, KeyPair, SizedBytes},
-    sized_bytes_using_constant_and_try_from,
+    keypair::{Key, KeyPair, SizedBytesExt},
+    serialization::{serialize, tokenize},
 };
-use digest::Digest;
+use digest::{Digest, FixedOutput};
 use generic_array::{
-    typenum::{U64, U96},
-    GenericArray,
+    typenum::{Unsigned, U32},
+    ArrayLength, GenericArray,
 };
+use generic_bytes::SizedBytes;
 use hkdf::Hkdf;
 use hmac::{Hmac, Mac, NewMac};
-use rand_core::{CryptoRng, RngCore};
+use rand::{CryptoRng, RngCore};
 
 use std::convert::TryFrom;
 
 const KEY_LEN: usize = 32;
-pub(crate) const NONCE_LEN: usize = 32;
-const KE1_STATE_LEN: usize = KEY_LEN + KEY_LEN + NONCE_LEN;
-const KE2_MESSAGE_LEN: usize = NONCE_LEN + 2 * KEY_LEN;
+pub(crate) type NonceLen = U32;
 
-static STR_3DH: &[u8] = b"3DH keys";
+static STR_3DH: &[u8] = b"3DH";
+static STR_CLIENT_MAC: &[u8] = b"client mac";
+static STR_HANDSHAKE_SECRET: &[u8] = b"handshake secret";
+static STR_SERVER_MAC: &[u8] = b"server mac";
+static STR_HANDSHAKE_ENC: &[u8] = b"handshake enc";
+static STR_ENCRYPTION_PAD: &[u8] = b"encryption pad";
+static STR_SESSION_SECRET: &[u8] = b"session secret";
+static STR_OPAQUE: &[u8] = b"OPAQUE ";
 
+#[allow(clippy::upper_case_acronyms)]
 /// The Triple Diffie-Hellman key exchange implementation
 pub struct TripleDH;
 
-impl<D: Hash> KeyExchange<D> for TripleDH {
-    type KE1State = KE1State;
-    type KE2State = KE2State;
-    type KE1Message = KE1Message;
-    type KE2Message = KE2Message;
-    type KE3Message = KE3Message;
+impl<D: Hash, G: Group> KeyExchange<D, G> for TripleDH {
+    type KE1State = Ke1State;
+    type KE2State = Ke2State<<D as FixedOutput>::OutputSize>;
+    type KE1Message = Ke1Message;
+    type KE2Message = Ke2Message<<D as FixedOutput>::OutputSize>;
+    type KE3Message = Ke3Message<<D as FixedOutput>::OutputSize>;
 
-    fn generate_ke1<R: RngCore + CryptoRng, KeyFormat: KeyPair<Repr = Key>>(
-        l1_component: Vec<u8>,
+    fn generate_ke1<R: RngCore + CryptoRng>(
+        info: Vec<u8>,
         rng: &mut R,
     ) -> Result<(Self::KE1State, Self::KE1Message), ProtocolError> {
-        let client_e_kp = KeyFormat::generate_random(rng)?;
-        let mut client_nonce = [0u8; NONCE_LEN];
-        rng.fill_bytes(&mut client_nonce);
+        let client_e_kp = KeyPair::<G>::generate_random(rng);
+        let client_nonce = generate_nonce::<R>(rng);
 
-        let ke1_message = KE1Message {
-            client_nonce: client_nonce.to_vec(),
+        let ke1_message = Ke1Message {
+            client_nonce,
+            info,
             client_e_pk: client_e_kp.public().clone(),
         };
 
-        let l1_data: Vec<u8> = [&l1_component[..], &ke1_message.to_bytes()].concat();
-        let mut hasher = D::new();
-        hasher.update(&l1_data);
-        let hashed_l1 = hasher.finalize();
-
         Ok((
-            KE1State {
+            Ke1State {
                 client_e_sk: client_e_kp.private().clone(),
-                client_nonce: client_nonce.to_vec(),
-                hashed_l1: hashed_l1.to_vec(),
+                client_nonce,
             },
             ke1_message,
         ))
     }
 
-    fn generate_ke2<R: RngCore + CryptoRng, KeyFormat: KeyPair<Repr = Key>>(
+    #[allow(clippy::type_complexity)]
+    fn generate_ke2<R: RngCore + CryptoRng>(
         rng: &mut R,
-        l1_bytes: Vec<u8>,
+        serialized_credential_request: Vec<u8>,
         l2_bytes: Vec<u8>,
         ke1_message: Self::KE1Message,
-        client_s_pk: KeyFormat::Repr,
-        server_s_sk: KeyFormat::Repr,
-    ) -> Result<(Self::KE2State, Self::KE2Message), ProtocolError> {
-        let server_e_kp = KeyFormat::generate_random(rng)?;
-        let mut server_nonce = [0u8; NONCE_LEN];
-        rng.fill_bytes(&mut server_nonce);
+        client_s_pk: Key,
+        server_s_sk: Key,
+        id_u: Vec<u8>,
+        id_s: Vec<u8>,
+        e_info: Vec<u8>,
+    ) -> Result<(Vec<u8>, Self::KE2State, Self::KE2Message), ProtocolError> {
+        let server_e_kp = KeyPair::<G>::generate_random(rng);
+        let server_nonce = generate_nonce::<R>(rng);
 
-        let (shared_secret, km2, km3) = derive_3dh_keys::<KeyFormat, D>(
+        let mut transcript_hasher = D::new()
+            .chain(STR_3DH)
+            .chain(&serialize(&id_u, 2))
+            .chain(&serialized_credential_request[..])
+            .chain(&serialize(&id_s, 2))
+            .chain(&l2_bytes[..])
+            .chain(&server_nonce[..])
+            .chain(&server_e_kp.public().to_arr());
+
+        let (session_key, km2, ke2, km3) = derive_3dh_keys::<D, G>(
             TripleDHComponents {
                 pk1: ke1_message.client_e_pk.clone(),
                 sk1: server_e_kp.private().clone(),
                 pk2: ke1_message.client_e_pk,
-                sk2: server_s_sk.clone(),
-                pk3: client_s_pk.clone(),
+                sk2: server_s_sk,
+                pk3: client_s_pk,
                 sk3: server_e_kp.private().clone(),
             },
-            &ke1_message.client_nonce,
-            &server_nonce,
-            client_s_pk,
-            KeyFormat::public_from_private(&server_s_sk),
+            &transcript_hasher.clone().finalize(),
         )?;
 
-        let mut hasher = D::new();
-        hasher.update(&l1_bytes);
-        let hashed_l1 = hasher.finalize();
+        // Compute encryption of e_info
+        let h = Hkdf::<D>::from_prk(&ke2).map_err(|_| InternalPakeError::HkdfError)?;
+        let mut encryption_pad = vec![0u8; e_info.len()];
+        h.expand(STR_ENCRYPTION_PAD, &mut encryption_pad)
+            .map_err(|_| InternalPakeError::HkdfError)?;
+        let ciphertext: Vec<u8> = encryption_pad
+            .iter()
+            .zip(e_info.iter())
+            .map(|(&x1, &x2)| x1 ^ x2)
+            .collect();
 
-        let transcript2: Vec<u8> = [
-            &hashed_l1[..],
-            &l2_bytes[..],
-            &server_nonce[..],
-            &server_e_kp.public().to_arr(),
-        ]
-        .concat();
+        transcript_hasher.update(&serialize(&ciphertext, 2));
 
-        let mut hasher2 = D::new();
-        hasher2.update(&transcript2);
-        let hashed_transcript = hasher2.finalize();
+        let mut mac_hasher =
+            Hmac::<D>::new_varkey(&km2).map_err(|_| InternalPakeError::HmacError)?;
+        mac_hasher.update(&transcript_hasher.clone().finalize());
+        let mac = mac_hasher.finalize().into_bytes();
 
-        let mut mac = Hmac::<D>::new_varkey(&km2).map_err(|_| InternalPakeError::HmacError)?;
-        mac.update(&hashed_transcript);
+        transcript_hasher.update(&mac);
 
         Ok((
-            KE2State {
-                km3: km3.to_vec(),
-                hashed_transcript: hashed_transcript.to_vec(),
-                shared_secret: shared_secret.to_vec(),
+            ke1_message.info,
+            Ke2State {
+                km3,
+                hashed_transcript: transcript_hasher.finalize(),
+                session_key,
             },
-            KE2Message {
-                server_nonce: server_nonce.to_vec(),
+            Ke2Message {
+                server_nonce,
                 server_e_pk: server_e_kp.public().clone(),
-                mac: mac.finalize().into_bytes().to_vec(),
+                e_info: ciphertext,
+                mac,
             },
         ))
     }
 
-    fn generate_ke3<KeyFormat: KeyPair<Repr = Key>>(
+    #[allow(clippy::type_complexity)]
+    fn generate_ke3(
         l2_component: Vec<u8>,
         ke2_message: Self::KE2Message,
         ke1_state: &Self::KE1State,
-        server_s_pk: KeyFormat::Repr,
-        client_s_sk: KeyFormat::Repr,
-    ) -> Result<(Vec<u8>, Self::KE3Message), ProtocolError> {
-        let (shared_secret, km2, km3) = derive_3dh_keys::<KeyFormat, D>(
+        serialized_credential_request: &[u8],
+        server_s_pk: Key,
+        client_s_sk: Key,
+        id_u: Vec<u8>,
+        id_s: Vec<u8>,
+    ) -> Result<(Vec<u8>, Vec<u8>, Self::KE3Message), ProtocolError> {
+        let mut transcript_hasher = D::new()
+            .chain(STR_3DH)
+            .chain(&serialize(&id_u, 2))
+            .chain(&serialized_credential_request)
+            .chain(&serialize(&id_s, 2))
+            .chain(&l2_component[..])
+            .chain(&ke2_message.to_bytes_without_info_or_mac());
+
+        let (session_key, km2, ke2, km3) = derive_3dh_keys::<D, G>(
             TripleDHComponents {
                 pk1: ke2_message.server_e_pk.clone(),
                 sk1: ke1_state.client_e_sk.clone(),
-                pk2: server_s_pk.clone(),
+                pk2: server_s_pk,
                 sk2: ke1_state.client_e_sk.clone(),
                 pk3: ke2_message.server_e_pk.clone(),
-                sk3: client_s_sk.clone(),
+                sk3: client_s_sk,
             },
-            &ke1_state.client_nonce,
-            &ke2_message.server_nonce,
-            KeyFormat::public_from_private(&client_s_sk),
-            server_s_pk,
+            &transcript_hasher.clone().finalize(),
         )?;
 
-        let transcript: Vec<u8> = [
-            &ke1_state.hashed_l1[..],
-            &l2_component[..],
-            &ke2_message.server_nonce[..],
-            &ke2_message.server_e_pk[..],
-        ]
-        .concat();
-
-        let mut hasher = D::new();
-        hasher.update(&transcript);
-        let hashed_transcript = hasher.finalize();
+        transcript_hasher.update(&serialize(&ke2_message.e_info[..], 2));
 
         let mut server_mac =
             Hmac::<D>::new_varkey(&km2).map_err(|_| InternalPakeError::HmacError)?;
-        server_mac.update(&hashed_transcript);
+        server_mac.update(&transcript_hasher.clone().finalize());
 
-        if ke2_message.mac != server_mac.finalize().into_bytes().to_vec() {
+        if ke2_message.mac != server_mac.finalize().into_bytes() {
             return Err(ProtocolError::VerificationError(
                 PakeError::KeyExchangeMacValidationError,
             ));
         }
 
+        transcript_hasher.update(ke2_message.mac.to_vec());
+
         let mut client_mac =
             Hmac::<D>::new_varkey(&km3).map_err(|_| InternalPakeError::HmacError)?;
-        client_mac.update(&hashed_transcript);
+        client_mac.update(&transcript_hasher.finalize());
+
+        // Compute decryption of e_info
+        let h = Hkdf::<D>::from_prk(&ke2).map_err(|_| InternalPakeError::HkdfError)?;
+        let mut encryption_pad = vec![0u8; ke2_message.e_info.len()];
+        h.expand(STR_ENCRYPTION_PAD, &mut encryption_pad)
+            .map_err(|_| InternalPakeError::HkdfError)?;
+        let plaintext: Vec<u8> = encryption_pad
+            .iter()
+            .zip(ke2_message.e_info.iter())
+            .map(|(&x1, &x2)| x1 ^ x2)
+            .collect();
 
         Ok((
-            shared_secret.to_vec(),
-            KE3Message {
-                mac: client_mac.finalize().into_bytes().to_vec(),
+            plaintext,
+            session_key.to_vec(),
+            Ke3Message {
+                mac: client_mac.finalize().into_bytes(),
             },
         ))
     }
 
+    #[allow(clippy::type_complexity)]
     fn finish_ke(
         ke3_message: Self::KE3Message,
         ke2_state: &Self::KE2State,
@@ -191,155 +222,172 @@ impl<D: Hash> KeyExchange<D> for TripleDH {
             Hmac::<D>::new_varkey(&ke2_state.km3).map_err(|_| InternalPakeError::HmacError)?;
         client_mac.update(&ke2_state.hashed_transcript);
 
-        if ke3_message.mac != client_mac.finalize().into_bytes().to_vec() {
+        if ke3_message.mac != client_mac.finalize().into_bytes() {
             return Err(ProtocolError::VerificationError(
                 PakeError::KeyExchangeMacValidationError,
             ));
         }
 
-        Ok(ke2_state.shared_secret.to_vec())
-    }
-
-    fn ke1_state_size() -> usize {
-        KE1_STATE_LEN
+        Ok(ke2_state.session_key.to_vec())
     }
 
     fn ke2_message_size() -> usize {
-        KE2_MESSAGE_LEN
+        NonceLen::to_usize() + KEY_LEN + <<D as FixedOutput>::OutputSize as Unsigned>::to_usize()
     }
 }
 
 /// The client state produced after the first key exchange message
 #[derive(PartialEq, Eq)]
-pub struct KE1State {
+pub struct Ke1State {
     client_e_sk: Key,
-    client_nonce: Vec<u8>,
-    hashed_l1: Vec<u8>,
+    client_nonce: GenericArray<u8, NonceLen>,
 }
 
 /// The first key exchange message
 #[derive(PartialEq, Eq)]
-pub struct KE1Message {
-    pub(crate) client_nonce: Vec<u8>,
+pub struct Ke1Message {
+    pub(crate) client_nonce: GenericArray<u8, NonceLen>,
+    pub(crate) info: Vec<u8>,
     pub(crate) client_e_pk: Key,
 }
 
-impl TryFrom<Vec<u8>> for KE1State {
-    type Error = InternalPakeError;
+impl TryFrom<&[u8]> for Ke1State {
+    type Error = PakeError;
 
-    fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
-        let checked_bytes = check_slice_size(&bytes, KE1_STATE_LEN, "ke1_state")?;
+    fn try_from(bytes: &[u8]) -> Result<Self, Self::Error> {
+        let nonce_len = NonceLen::to_usize();
+        let checked_bytes = check_slice_size_atleast(bytes, KEY_LEN + nonce_len, "ke1_state")?;
 
         Ok(Self {
             client_e_sk: Key::from_bytes(&checked_bytes[..KEY_LEN])?,
-            client_nonce: checked_bytes[KEY_LEN..KEY_LEN + NONCE_LEN].to_vec(),
-            hashed_l1: checked_bytes[KEY_LEN + NONCE_LEN..].to_vec(),
+            client_nonce: GenericArray::clone_from_slice(
+                &checked_bytes[KEY_LEN..KEY_LEN + nonce_len],
+            ),
         })
     }
 }
 
-impl ToBytes for KE1State {
+impl ToBytes for Ke1State {
     fn to_bytes(&self) -> Vec<u8> {
-        let output: Vec<u8> = [
-            &self.client_e_sk.to_arr(),
-            &self.client_nonce[..],
-            &self.hashed_l1[..],
-        ]
-        .concat();
+        let output: Vec<u8> = [&self.client_e_sk.to_arr(), &self.client_nonce[..]].concat();
         output
     }
 }
 
-sized_bytes_using_constant_and_try_from!(KE1State, U96);
-
-impl ToBytes for KE1Message {
+impl ToBytes for Ke1Message {
     fn to_bytes(&self) -> Vec<u8> {
-        [&self.client_nonce[..], &self.client_e_pk.to_arr()].concat()
+        [
+            &self.client_nonce[..],
+            &serialize(&self.info, 2),
+            &self.client_e_pk.to_arr(),
+        ]
+        .concat()
     }
 }
 
-impl TryFrom<Vec<u8>> for KE1Message {
-    type Error = InternalPakeError;
+impl TryFrom<&[u8]> for Ke1Message {
+    type Error = PakeError;
 
-    fn try_from(ke1_message_bytes: Vec<u8>) -> Result<Self, Self::Error> {
-        let checked_bytes =
-            check_slice_size(&ke1_message_bytes, NONCE_LEN + KEY_LEN, "ke1_message")?;
+    fn try_from(ke1_message_bytes: &[u8]) -> Result<Self, Self::Error> {
+        let nonce_len = NonceLen::to_usize();
+        let checked_nonce =
+            check_slice_size_atleast(ke1_message_bytes, nonce_len, "ke1_message nonce")?;
+
+        let (info, remainder) = tokenize(&checked_nonce[nonce_len..], 2)?;
+
+        let checked_client_e_pk = check_slice_size(&remainder, KEY_LEN, "ke1_message client_e_pk")?;
 
         Ok(Self {
-            client_nonce: checked_bytes[..NONCE_LEN].to_vec(),
-            client_e_pk: Key::from_bytes(&checked_bytes[NONCE_LEN..])?,
+            client_nonce: GenericArray::clone_from_slice(&checked_nonce[..nonce_len]),
+            info,
+            client_e_pk: Key::from_bytes(&checked_client_e_pk)?,
         })
     }
 }
-
-sized_bytes_using_constant_and_try_from!(KE1Message, U64);
-
 /// The server state produced after the second key exchange message
-pub struct KE2State {
-    km3: Vec<u8>,
-    hashed_transcript: Vec<u8>,
-    shared_secret: Vec<u8>,
+pub struct Ke2State<HashLen: ArrayLength<u8>> {
+    km3: GenericArray<u8, HashLen>,
+    hashed_transcript: GenericArray<u8, HashLen>,
+    session_key: GenericArray<u8, HashLen>,
 }
 
 /// The second key exchange message
-pub struct KE2Message {
-    server_nonce: Vec<u8>,
+pub struct Ke2Message<HashLen: ArrayLength<u8>> {
+    server_nonce: GenericArray<u8, NonceLen>,
     server_e_pk: Key,
-    mac: Vec<u8>,
+    e_info: Vec<u8>,
+    mac: GenericArray<u8, HashLen>,
 }
 
-impl ToBytes for KE2State {
+impl<HashLen: ArrayLength<u8>> ToBytes for Ke2State<HashLen> {
     fn to_bytes(&self) -> Vec<u8> {
-        let output: Vec<u8> = [
+        [
             &self.km3[..],
             &self.hashed_transcript[..],
-            &self.shared_secret[..],
+            &self.session_key[..],
         ]
-        .concat();
-        output
+        .concat()
     }
 }
 
-impl TryFrom<Vec<u8>> for KE2State {
-    type Error = ProtocolError;
+impl<HashLen: ArrayLength<u8>> TryFrom<&[u8]> for Ke2State<HashLen> {
+    type Error = PakeError;
 
-    fn try_from(ke1_message_bytes: Vec<u8>) -> Result<Self, Self::Error> {
-        let checked_bytes = check_slice_size(&ke1_message_bytes, 3 * KEY_LEN, "ke2_state")?;
+    fn try_from(input: &[u8]) -> Result<Self, Self::Error> {
+        let hash_len = HashLen::to_usize();
+        let checked_bytes = check_slice_size(input, 3 * hash_len, "ke2_state")?;
 
         Ok(Self {
-            km3: checked_bytes[..KEY_LEN].to_vec(),
-            hashed_transcript: checked_bytes[KEY_LEN..2 * KEY_LEN].to_vec(),
-            shared_secret: checked_bytes[2 * KEY_LEN..].to_vec(),
+            km3: GenericArray::clone_from_slice(&checked_bytes[..hash_len]),
+            hashed_transcript: GenericArray::clone_from_slice(
+                &checked_bytes[hash_len..2 * hash_len],
+            ),
+            session_key: GenericArray::clone_from_slice(&checked_bytes[2 * hash_len..3 * hash_len]),
         })
     }
 }
 
-impl ToBytes for KE2Message {
+impl<HashLen: ArrayLength<u8>> ToBytes for Ke2Message<HashLen> {
     fn to_bytes(&self) -> Vec<u8> {
-        let output: Vec<u8> = [
-            &self.server_nonce[..],
-            &self.server_e_pk.to_arr(),
+        [
+            &self.to_bytes_without_info_or_mac(),
+            &serialize(&self.e_info, 2),
             &self.mac[..],
         ]
-        .concat();
-        output
+        .concat()
     }
 }
 
-impl TryFrom<Vec<u8>> for KE2Message {
-    type Error = ProtocolError;
+impl<HashLen: ArrayLength<u8>> Ke2Message<HashLen> {
+    fn to_bytes_without_info_or_mac(&self) -> Vec<u8> {
+        [&self.server_nonce[..], &self.server_e_pk.to_arr()].concat()
+    }
+}
 
-    fn try_from(ke2_message_bytes: Vec<u8>) -> Result<Self, Self::Error> {
-        let checked_bytes = check_slice_size(&ke2_message_bytes, KE2_MESSAGE_LEN, "ke2_message")?;
+impl<HashLen: ArrayLength<u8>> TryFrom<&[u8]> for Ke2Message<HashLen> {
+    type Error = PakeError;
+
+    fn try_from(input: &[u8]) -> Result<Self, Self::Error> {
+        let nonce_len = NonceLen::to_usize();
+        let checked_nonce = check_slice_size_atleast(input, nonce_len, "ke2_message nonce")?;
+        let checked_server_e_pk = check_slice_size_atleast(
+            &checked_nonce[nonce_len..],
+            KEY_LEN,
+            "ke2_message server_e_pk",
+        )?;
+        let (e_info, remainder) = tokenize(&checked_server_e_pk[KEY_LEN..], 2)?;
+        let checked_mac = check_slice_size(&remainder, HashLen::to_usize(), "ke1_message mac")?;
 
         Ok(Self {
-            server_nonce: checked_bytes[..NONCE_LEN].to_vec(),
-            server_e_pk: Key::from_bytes(&checked_bytes[NONCE_LEN..NONCE_LEN + KEY_LEN])?,
-            mac: checked_bytes[NONCE_LEN + KEY_LEN..].to_vec(),
+            server_nonce: GenericArray::clone_from_slice(&checked_nonce[..nonce_len]),
+            server_e_pk: Key::from_bytes(&checked_server_e_pk[..KEY_LEN])?,
+            e_info,
+            mac: GenericArray::clone_from_slice(&checked_mac),
         })
     }
 }
 
+#[allow(clippy::upper_case_acronyms)]
 // The triple of public and private components used in the 3DH computation
 struct TripleDHComponents {
     pk1: Key,
@@ -350,69 +398,141 @@ struct TripleDHComponents {
     sk3: Key,
 }
 
-// Consists of a shared secret, followed by two mac keys
+#[allow(clippy::upper_case_acronyms)]
+// Consists of a session key, followed by two mac keys and an encryption key: (session_key, km2, ke2, km3)
 type TripleDHDerivationResult<D> = (
-    GenericArray<u8, <D as Hash>::OutputSize>,
-    GenericArray<u8, <D as Hash>::OutputSize>,
-    GenericArray<u8, <D as Hash>::OutputSize>,
+    GenericArray<u8, <D as FixedOutput>::OutputSize>,
+    GenericArray<u8, <D as FixedOutput>::OutputSize>,
+    GenericArray<u8, <D as FixedOutput>::OutputSize>,
+    GenericArray<u8, <D as FixedOutput>::OutputSize>,
 );
 
-// Internal function which takes the public and private components of the client and server keypairs, along
-// with some auxiliary metadata, to produce the shared secret and two MAC keys
-fn derive_3dh_keys<KeyFormat: KeyPair<Repr = Key>, D: Hash>(
-    dh: TripleDHComponents,
-    client_nonce: &[u8],
-    server_nonce: &[u8],
-    client_s_pk: KeyFormat::Repr,
-    server_s_pk: KeyFormat::Repr,
-) -> Result<TripleDHDerivationResult<D>, ProtocolError> {
-    let ikm: Vec<u8> = [
-        &KeyFormat::diffie_hellman(dh.pk1, dh.sk1)[..],
-        &KeyFormat::diffie_hellman(dh.pk2, dh.sk2)[..],
-        &KeyFormat::diffie_hellman(dh.pk3, dh.sk3)[..],
-    ]
-    .concat();
-
-    let info: Vec<u8> = [
-        STR_3DH,
-        &client_nonce,
-        &server_nonce,
-        &client_s_pk.to_arr(),
-        &server_s_pk.to_arr(),
-    ]
-    .concat();
-
-    const OUTPUT_SIZE: usize = 32;
-    let mut okm = [0u8; 3 * OUTPUT_SIZE];
-    let h = Hkdf::<D>::new(None, &ikm);
-    h.expand(&info, &mut okm)
-        .map_err(|_| InternalPakeError::HkdfError)?;
-    Ok((
-        GenericArray::clone_from_slice(&okm[..OUTPUT_SIZE]),
-        GenericArray::clone_from_slice(&okm[OUTPUT_SIZE..2 * OUTPUT_SIZE]),
-        GenericArray::clone_from_slice(&okm[2 * OUTPUT_SIZE..]),
-    ))
-}
-
 /// The third key exchange message
-pub struct KE3Message {
-    mac: Vec<u8>,
+pub struct Ke3Message<HashLen: ArrayLength<u8>> {
+    mac: GenericArray<u8, HashLen>,
 }
 
-impl ToBytes for KE3Message {
+impl<HashLen: ArrayLength<u8>> ToBytes for Ke3Message<HashLen> {
     fn to_bytes(&self) -> Vec<u8> {
-        self.mac.clone()
+        self.mac.to_vec()
     }
 }
 
-impl TryFrom<Vec<u8>> for KE3Message {
-    type Error = ProtocolError;
+impl<HashLen: ArrayLength<u8>> TryFrom<&[u8]> for Ke3Message<HashLen> {
+    type Error = PakeError;
 
-    fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
-        let checked_bytes = check_slice_size(&bytes, KEY_LEN, "ke3_message")?;
+    fn try_from(bytes: &[u8]) -> Result<Self, Self::Error> {
+        let checked_bytes = check_slice_size(&bytes, HashLen::to_usize(), "ke3_message")?;
 
         Ok(Self {
-            mac: checked_bytes.to_vec(),
+            mac: GenericArray::clone_from_slice(&checked_bytes),
         })
     }
 }
+
+// Helper functions
+
+// Internal function which takes the public and private components of the client and server keypairs, along
+// with some auxiliary metadata, to produce the session key and two MAC keys
+fn derive_3dh_keys<D: Hash, G: Group>(
+    dh: TripleDHComponents,
+    hashed_derivation_transcript: &[u8],
+) -> Result<TripleDHDerivationResult<D>, ProtocolError> {
+    let ikm: Vec<u8> = [
+        &KeyPair::<G>::diffie_hellman(dh.pk1, dh.sk1)?[..],
+        &KeyPair::<G>::diffie_hellman(dh.pk2, dh.sk2)?[..],
+        &KeyPair::<G>::diffie_hellman(dh.pk3, dh.sk3)?[..],
+    ]
+    .concat();
+
+    let extracted_ikm = Hkdf::<D>::new(None, &ikm);
+    let handshake_secret = derive_secrets::<D>(
+        &extracted_ikm,
+        &STR_HANDSHAKE_SECRET,
+        &hashed_derivation_transcript,
+    )?;
+    let session_key = derive_secrets::<D>(
+        &extracted_ikm,
+        &STR_SESSION_SECRET,
+        &hashed_derivation_transcript,
+    )?;
+
+    let km2 = hkdf_expand_label::<D>(
+        &handshake_secret,
+        &STR_SERVER_MAC,
+        b"",
+        <D as Digest>::OutputSize::to_usize(),
+    )?;
+    let ke2 = hkdf_expand_label::<D>(
+        &handshake_secret,
+        &STR_HANDSHAKE_ENC,
+        b"",
+        <D as Digest>::OutputSize::to_usize(),
+    )?;
+    let km3 = hkdf_expand_label::<D>(
+        &handshake_secret,
+        &STR_CLIENT_MAC,
+        b"",
+        <D as Digest>::OutputSize::to_usize(),
+    )?;
+
+    Ok((
+        GenericArray::clone_from_slice(&session_key),
+        GenericArray::clone_from_slice(&km2),
+        GenericArray::clone_from_slice(&ke2),
+        GenericArray::clone_from_slice(&km3),
+    ))
+}
+
+fn hkdf_expand_label<D: Hash>(
+    secret: &[u8],
+    label: &[u8],
+    context: &[u8],
+    length: usize,
+) -> Result<Vec<u8>, ProtocolError> {
+    let h = Hkdf::<D>::from_prk(secret).map_err(|_| InternalPakeError::HkdfError)?;
+    hkdf_expand_label_extracted(&h, label, context, length)
+}
+
+fn hkdf_expand_label_extracted<D: Hash>(
+    hkdf: &Hkdf<D>,
+    label: &[u8],
+    context: &[u8],
+    length: usize,
+) -> Result<Vec<u8>, ProtocolError> {
+    let mut okm = vec![0u8; length];
+
+    let mut hkdf_label: Vec<u8> = Vec::new();
+    hkdf_label.extend_from_slice(&length.to_be_bytes()[std::mem::size_of::<usize>() - 2..]);
+
+    let mut opaque_label: Vec<u8> = Vec::new();
+    opaque_label.extend_from_slice(&STR_OPAQUE);
+    opaque_label.extend_from_slice(&label);
+    hkdf_label.extend_from_slice(&serialize(&opaque_label, 1));
+
+    hkdf_label.extend_from_slice(&serialize(&context, 1));
+
+    hkdf.expand(&hkdf_label, &mut okm)
+        .map_err(|_| InternalPakeError::HkdfError)?;
+    Ok(okm)
+}
+
+fn derive_secrets<D: Hash>(
+    hkdf: &Hkdf<D>,
+    label: &[u8],
+    hashed_derivation_transcript: &[u8],
+) -> Result<Vec<u8>, ProtocolError> {
+    hkdf_expand_label_extracted::<D>(
+        hkdf,
+        label,
+        &hashed_derivation_transcript,
+        <D as Digest>::OutputSize::to_usize(),
+    )
+}
+
+// Generate a random nonce up to NonceLen::to_usize() bytes.
+fn generate_nonce<R: RngCore + CryptoRng>(rng: &mut R) -> GenericArray<u8, NonceLen> {
+    let mut nonce_bytes = vec![0u8; NonceLen::to_usize()];
+    rng.fill_bytes(&mut nonce_bytes);
+    GenericArray::clone_from_slice(&nonce_bytes)
+}

src/keypair.rs

@@ -5,73 +5,104 @@
 
 //! Contains the keypair types that must be supplied for the OPAQUE API
 
-use crate::errors::{utils::check_slice_size, InternalPakeError};
-use generic_array::{
-    sequence::Concat,
-    typenum::{Sum, Unsigned, U32},
-    ArrayLength, GenericArray,
-};
+use crate::errors::InternalPakeError;
+use crate::group::Group;
+use generic_array::{typenum::U32, GenericArray};
+use generic_bytes::{SizedBytes, TryFromSizedBytesError};
 #[cfg(test)]
 use proptest::prelude::*;
 #[cfg(test)]
 use rand::{rngs::StdRng, SeedableRng};
-use rand_core::{CryptoRng, RngCore};
+use rand::{CryptoRng, RngCore};
 use std::fmt::Debug;
-use x25519_dalek::{PublicKey, StaticSecret};
+use std::marker::PhantomData;
+use std::ops::Deref;
 
-use std::convert::TryFrom;
-
-use std::ops::{Add, Deref};
-
-/// A trait for sized key material that can be represented within a fixed byte
-/// array size, used to represent our DH key types
-pub trait SizedBytes: Sized + PartialEq {
-    /// The typed representation of the byte length
-    type Len: ArrayLength<u8>;
-
-    /// Converts this sized key material to a `GenericArray` of the same
-    /// size. One can convert this to a `&[u8]` with `GenericArray::as_slice()`
-    /// but the size information is then lost from the type.
-    fn to_arr(&self) -> GenericArray<u8, Self::Len>;
-
-    /// How to parse such sized material from a byte slice.
-    fn from_bytes(key_bytes: &[u8]) -> Result<Self, InternalPakeError>;
+/// Convenience extension trait of SizedBytes
+pub trait SizedBytesExt: SizedBytes {
+    /// Convert from bytes
+    fn from_bytes(bytes: &[u8]) -> Result<Self, TryFromSizedBytesError> {
+        <Self as SizedBytes>::from_arr(GenericArray::from_slice(bytes))
+    }
 }
 
-/// A Keypair trait with public-private verification
-pub trait KeyPair: Sized {
-    /// The single key representation must have a specific byte size itself
-    type Repr: SizedBytes + Clone;
+// blanket implementation
+impl<T> SizedBytesExt for T where T: SizedBytes {}
 
+/// A Keypair trait with public-private verification
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct KeyPair<G> {
+    pk: Key,
+    sk: Key,
+    _g: PhantomData<G>,
+}
+
+impl<G: Group> KeyPair<G> {
     /// The public key component
-    fn public(&self) -> &Self::Repr;
+    pub fn public(&self) -> &Key {
+        &self.pk
+    }
 
     /// The private key component
-    fn private(&self) -> &Self::Repr;
+    pub fn private(&self) -> &Key {
+        &self.sk
+    }
 
     /// A constructor that receives public and private key independently as
     /// bytes
-    fn new(public: Self::Repr, private: Self::Repr) -> Result<Self, InternalPakeError>;
+    pub fn new(public: Key, private: Key) -> Result<Self, InternalPakeError> {
+        Ok(Self {
+            pk: public,
+            sk: private,
+            _g: PhantomData,
+        })
+    }
 
     /// Generating a random key pair given a cryptographic rng
-    fn generate_random<R: RngCore + CryptoRng>(rng: &mut R) -> Result<Self, InternalPakeError>;
+    pub(crate) fn generate_random<R: RngCore + CryptoRng>(rng: &mut R) -> Self {
+        let sk = G::random_scalar(rng);
+        let sk_bytes = G::scalar_as_bytes(&sk);
+        let pk = G::base_point().mult_by_slice(&sk_bytes);
+        Self {
+            pk: Key(pk.to_arr().to_vec()),
+            sk: Key(sk_bytes.to_vec()),
+            _g: PhantomData,
+        }
+    }
 
     /// Obtaining a public key from secret bytes. At all times, we should have
     /// &public_from_private(self.private()) == self.public()
-    fn public_from_private(secret: &Self::Repr) -> Self::Repr;
+    pub(crate) fn public_from_private(bytes: &Key) -> Key {
+        let bytes_data = GenericArray::<u8, G::ScalarLen>::from_slice(&bytes.0[..]);
+        Key(G::base_point().mult_by_slice(&bytes_data).to_arr().to_vec())
+    }
 
     /// Check whether a public key is valid. This is meant to be applied on
     /// material provided through the network which fits the key
     /// representation (i.e. can be mapped to a curve point), but presents
     /// some risk - e.g. small subgroup check
-    fn check_public_key(key: Self::Repr) -> Result<Self::Repr, InternalPakeError>;
+    pub(crate) fn check_public_key(key: Key) -> Result<Key, InternalPakeError> {
+        G::from_element_slice(GenericArray::from_slice(&key.0)).map(|_| key)
+    }
 
     /// Computes the diffie hellman function on a public key and private key
-    fn diffie_hellman(pk: Self::Repr, sk: Self::Repr) -> Vec<u8>;
+    pub(crate) fn diffie_hellman(pk: Key, sk: Key) -> Result<Vec<u8>, InternalPakeError> {
+        let pk_data = GenericArray::<u8, G::ElemLen>::from_slice(&pk.0[..]);
+        let point = G::from_element_slice(&pk_data)?;
+        let secret_data = GenericArray::<u8, G::ScalarLen>::from_slice(&sk.0[..]);
+        Ok(G::mult_by_slice(&point, &secret_data).to_arr().to_vec())
+    }
+
+    /// Obtains a KeyPair from a slice representing the private key
+    pub fn from_private_key_slice(input: &[u8]) -> Result<Self, InternalPakeError> {
+        let sk = Key::from_arr(GenericArray::from_slice(&input))?;
+        let pk = Self::public_from_private(&sk);
+        Self::new(pk, sk)
+    }
 }
 
 #[cfg(test)]
-trait KeyPairExt: KeyPair + Debug {
+impl<G: Group + Debug> KeyPair<G> {
     /// Test-only strategy returning a proptest Strategy based on
     /// generate_random
     fn uniform_keypair_strategy() -> BoxedStrategy<Self> {
@@ -80,101 +111,14 @@ trait KeyPairExt: KeyPair + Debug {
         any::<[u8; 32]>()
             .prop_filter_map("valid random keypair", |seed| {
                 let mut rng = StdRng::from_seed(seed);
-                Self::generate_random(&mut rng).ok()
+                Some(Self::generate_random(&mut rng))
             })
             .no_shrink()
             .boxed()
     }
 }
 
-// blanket implementation
-#[cfg(test)]
-impl<KP> KeyPairExt for KP where KP: KeyPair + Debug {}
-
-/// This assumes you have defined:
-/// - an `impl TryFrom<&[u8b], Error = InternalPakeError>` for a non-generic `T`
-/// - an `fn to_bytes(&self) -> Vec<u8>` in an `impl T` block
-/// and it both of the above to produce a sensible SizedBytes implementation
-///
-/// Because SizedBytes has a strong notion of size, and TryFrom/to_bytes does
-/// not, it's better to use the macro below rather than this one, where possible.
-#[macro_export]
-macro_rules! sized_bytes_using_constant_and_try_from {
-    ($sized_type: ident, $len: ident) => {
-        impl SizedBytes for $sized_type {
-            type Len = $len;
-
-            fn to_arr(&self) -> generic_array::GenericArray<u8, Self::Len> {
-                generic_array::GenericArray::clone_from_slice(&self.to_bytes())
-            }
-
-            fn from_bytes(bytes: &[u8]) -> Result<Self, InternalPakeError> {
-                let checked_bytes = check_slice_size(
-                    bytes,
-                    <Self::Len as generic_array::typenum::Unsigned>::to_usize(),
-                    "bytes",
-                )?;
-                std::convert::TryFrom::try_from(checked_bytes.to_vec())
-            }
-        }
-    };
-}
-
-/// This assumes you have defined a SizedBytes instance for a `T`, and defines:
-/// - an `impl TryFrom<&[u8b], Error = InternalPakeError>` for a non-generic `T`
-/// - an `fn to_bytes(&self) -> Vec<u8>` in an `impl T` block
-///
-/// Because SizedBytes has a strong notion of size, and TryFrom/to_bytes does
-/// not, it's better to use this macro than the one above, where possible.
-macro_rules! try_from_and_to_bytes_using_sized_bytes {
-    ($sized_type: ident) => {
-        impl TryFrom<&[u8]> for $sized_type {
-            type Error = InternalPakeError;
-
-            fn try_from(bytes: &[u8]) -> Result<Self, InternalPakeError> {
-                <$sized_type as SizedBytes>::from_bytes(bytes)
-            }
-        }
-
-        #[allow(dead_code)]
-        impl $sized_type {
-            fn to_bytes(&self) -> Vec<u8> {
-                self.to_arr().to_vec()
-            }
-        }
-    };
-}
-
-/// This is a blanket implementation of SizedBytes for any instance of KeyPair
-/// with any length of keys. This encodes that we serialize the public key
-/// first, followed by the private key in binary formats (and expect it in this
-/// order upon decoding).
-impl<T, KP> SizedBytes for KP
-where
-    T: SizedBytes + Clone,
-    KP: KeyPair<Repr = T> + PartialEq,
-    T::Len: Add<T::Len>,
-    Sum<T::Len, T::Len>: ArrayLength<u8>,
-{
-    type Len = Sum<T::Len, T::Len>;
-
-    fn to_arr(&self) -> GenericArray<u8, Self::Len> {
-        let private = self.private().to_arr();
-        let public = self.public().to_arr();
-        public.concat(private)
-    }
-
-    fn from_bytes(key_bytes: &[u8]) -> Result<Self, InternalPakeError> {
-        let checked_bytes =
-            check_slice_size(key_bytes, <Self::Len as Unsigned>::to_usize(), "key_bytes")?;
-        let single_key_len = <<KP::Repr as SizedBytes>::Len as Unsigned>::to_usize();
-        let public = <T as SizedBytes>::from_bytes(&checked_bytes[..single_key_len])?;
-        let private = <T as SizedBytes>::from_bytes(&checked_bytes[single_key_len..])?;
-        KP::new(public, private)
-    }
-}
-
-/// A minimalist key type built around [u8;32]
+/// A minimalist key type built around a \[u8; 32\]
 #[derive(Debug, PartialEq, Eq, Clone)]
 #[repr(transparent)]
 pub struct Key(Vec<u8>);
@@ -194,112 +138,48 @@ impl SizedBytes for Key {
         GenericArray::clone_from_slice(&self.0[..])
     }
 
-    fn from_bytes(key_bytes: &[u8]) -> Result<Self, InternalPakeError> {
-        let checked_bytes =
-            check_slice_size(key_bytes, <Self::Len as Unsigned>::to_usize(), "key_bytes")?;
-        Ok(Key(checked_bytes.to_vec()))
-    }
-}
-
-try_from_and_to_bytes_using_sized_bytes!(Key);
-
-/// A representation of an X25519 keypair according to RFC7748
-#[derive(Debug, PartialEq, Eq)]
-pub struct X25519KeyPair {
-    pk: Key,
-    sk: Key,
-}
-
-impl X25519KeyPair {
-    fn gen<R: RngCore + CryptoRng>(rng: &mut R) -> (Vec<u8>, Vec<u8>) {
-        let sk = StaticSecret::new(rng);
-        let pk = PublicKey::from(&sk);
-        (pk.as_bytes().to_vec(), sk.to_bytes().to_vec())
-    }
-}
-
-impl KeyPair for X25519KeyPair {
-    type Repr = Key;
-
-    fn public(&self) -> &Self::Repr {
-        &self.pk
-    }
-
-    fn private(&self) -> &Self::Repr {
-        &self.sk
-    }
-
-    fn new(public: Self::Repr, private: Self::Repr) -> Result<Self, InternalPakeError> {
-        Ok(X25519KeyPair {
-            pk: public,
-            sk: private,
-        })
-    }
-
-    fn generate_random<R: RngCore + CryptoRng>(rng: &mut R) -> Result<Self, InternalPakeError> {
-        let (public, private) = X25519KeyPair::gen(rng);
-        Ok(X25519KeyPair {
-            pk: Key(public),
-            sk: Key(private),
-        })
-    }
-
-    fn public_from_private(secret: &Self::Repr) -> Self::Repr {
-        let mut secret_data = [0u8; 32];
-        secret_data.copy_from_slice(&secret.0[..]);
-        let base_data = ::x25519_dalek::X25519_BASEPOINT_BYTES;
-        Key(::x25519_dalek::x25519(secret_data, base_data).to_vec())
-    }
-
-    fn check_public_key(key: Self::Repr) -> Result<Self::Repr, InternalPakeError> {
-        let mut key_bytes = [0u8; 32];
-        key_bytes.copy_from_slice(&key);
-        let point = ::curve25519_dalek::montgomery::MontgomeryPoint(key_bytes)
-            .to_edwards(1)
-            .ok_or(InternalPakeError::PointError)?;
-        if !point.is_torsion_free() {
-            Err(InternalPakeError::SubGroupError)
-        } else {
-            Ok(key)
-        }
-    }
-
-    fn diffie_hellman(pk: Self::Repr, sk: Self::Repr) -> Vec<u8> {
-        let mut pk_data = [0; 32];
-        pk_data.copy_from_slice(&pk.0[..]);
-        let mut sk_data = [0; 32];
-        sk_data.copy_from_slice(&sk.0[..]);
-        ::x25519_dalek::x25519(sk_data, pk_data).to_vec()
+    fn from_arr(key_bytes: &GenericArray<u8, Self::Len>) -> Result<Self, TryFromSizedBytesError> {
+        Ok(Key(key_bytes.to_vec()))
     }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
+    use curve25519_dalek::ristretto::RistrettoPoint;
 
     proptest! {
         #[test]
-        fn test_x25519_check(kp in X25519KeyPair::uniform_keypair_strategy()) {
+        fn test_ristretto_check(kp in KeyPair::<RistrettoPoint>::uniform_keypair_strategy()) {
             let pk = kp.public();
-            prop_assert!(X25519KeyPair::check_public_key(pk.clone()).is_ok());
+            prop_assert!(KeyPair::<RistrettoPoint>::check_public_key(pk.clone()).is_ok());
         }
 
         #[test]
-        fn test_x25519_pub_from_priv(kp in X25519KeyPair::uniform_keypair_strategy()) {
+        fn test_ristretto_pub_from_priv(kp in KeyPair::<RistrettoPoint>::uniform_keypair_strategy()) {
             let pk = kp.public();
             let sk = kp.private();
-            prop_assert_eq!(&X25519KeyPair::public_from_private(sk), pk);
+            prop_assert_eq!(&KeyPair::<RistrettoPoint>::public_from_private(sk), pk);
         }
 
+        #[test]
+        fn test_ristretto_dh(kp1 in KeyPair::<RistrettoPoint>::uniform_keypair_strategy(),
+                          kp2 in KeyPair::<RistrettoPoint>::uniform_keypair_strategy()) {
+
+            let dh1 = KeyPair::<RistrettoPoint>::diffie_hellman(kp1.public().clone(), kp2.private().clone())?;
+            let dh2 = KeyPair::<RistrettoPoint>::diffie_hellman(kp2.public().clone(), kp1.private().clone())?;
+
+            prop_assert_eq!(dh1, dh2);
+        }
 
         #[test]
-        fn test_x25519_dh(kp1 in X25519KeyPair::uniform_keypair_strategy(),
-                          kp2 in X25519KeyPair::uniform_keypair_strategy()) {
+        fn test_private_key_slice(kp in KeyPair::<RistrettoPoint>::uniform_keypair_strategy()) {
+            let sk_bytes = kp.private().to_vec();
 
-            let dh1 = X25519KeyPair::diffie_hellman(kp1.public().clone(), kp2.private().clone());
-            let dh2 = X25519KeyPair::diffie_hellman(kp2.public().clone(), kp1.private().clone());
+            let kp2 = KeyPair::<RistrettoPoint>::from_private_key_slice(&sk_bytes)?;
+            let kp2_private_bytes = kp2.private().to_vec();
 
-            prop_assert_eq!(dh1,dh2);
+            prop_assert_eq!(sk_bytes, kp2_private_bytes);
         }
     }
 }

src/lib.rs

@@ -5,7 +5,7 @@
 
 //! An implementation of the OPAQUE asymmetric password authentication key exchange protocol
 //!
-//! Note: This implementation is in sync with [draft-krawczyk-cfrg-opaque-06](https://tools.ietf.org/html/draft-krawczyk-cfrg-opaque-06),
+//! Note: This implementation is in sync with [draft-irtf-cfrg-opaque-03](https://www.ietf.org/archive/id/draft-irtf-cfrg-opaque-03.html),
 //! but this specification is subject to change, until the final version published by the IETF.
 //!
 //! # Overview
@@ -13,7 +13,6 @@
 //! OPAQUE is a protocol between a client and a server. They must first agree on a collection of primitives
 //! to be kept consistent throughout protocol execution. These include:
 //! * a finite cyclic group along with a point representation,
-//! * a keypair type,
 //! * a key exchange protocol,
 //! * a hashing function, and
 //! * a slow hashing function.
@@ -24,374 +23,681 @@
 //! struct Default;
 //! impl CipherSuite for Default {
 //!     type Group = curve25519_dalek::ristretto::RistrettoPoint;
-//!     type KeyFormat = opaque_ke::keypair::X25519KeyPair;
 //!     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
-//!     type Hash = sha2::Sha256;
+//!     type Hash = sha2::Sha512;
 //!     type SlowHash = opaque_ke::slow_hash::NoOpHash;
 //! }
 //! ```
+//! See [examples/simple_login.rs](https://github.com/novifinancial/opaque-ke/blob/master/examples/simple_login.rs)
+//! for a working example of a simple password-based login using OPAQUE.
 //!
 //! Note that our choice of slow hashing function in this example, `NoOpHash`, is selected only to ensure
-//! that the tests execute quickly. A real application should use an actual slow hashing function, such as `Scrypt`.
-//!
-//! We have included a concrete instantiation of the authenticated key exchange protocol using 3DH. In the future, we plan to
-//! add support for other KE protocols as well.
+//! that the tests execute quickly. A real application should use an actual slow hashing function, such as `scrypt`,
+//! which can be enabled through the `slow-hash` feature.
 //!
 //! ## Setup
-//! To setup the protocol, the server begins by generating a static keypair:
+//! To set up the protocol, the server begins by generating a static keypair:
 //! ```
-//! # use opaque_ke::keypair::{KeyPair, X25519KeyPair, SizedBytes};
 //! # use opaque_ke::errors::ProtocolError;
 //! # use opaque_ke::ciphersuite::CipherSuite;
 //! # struct Default;
 //! # impl CipherSuite for Default {
 //! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
-//! #     type KeyFormat = opaque_ke::keypair::X25519KeyPair;
 //! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
-//! #     type Hash = sha2::Sha256;
+//! #     type Hash = sha2::Sha512;
 //! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
 //! # }
-//! use rand_core::{OsRng, RngCore};
+//! use rand::{rngs::OsRng, RngCore};
 //! let mut rng = OsRng;
-//! let server_kp = Default::generate_random_keypair(&mut rng)?;
+//! let server_kp = Default::generate_random_keypair(&mut rng);
 //! # Ok::<(), ProtocolError>(())
 //! ```
 //! The server must persist this keypair for the registration and login steps, where the public component will be
 //! used by the client during both registration and login, and the private component will be used by the server during login.
 //!
 //! ## Registration
-//! The registration protocol between the client and server consists of four steps along with three messages, denoted
-//! as `r1`, `r2`, and `r3`. Before registration begins, it is expected that the server's static public key, `server_kp.public()`,
-//! has been transmitted to the client in an offline step. A successful execution of the registration protocol results in the
-//! server producing a password file corresponding to the tuple combination of (password, pepper, server public key) provided by
+//! The registration protocol between the client and server consists of four steps along with three messages:
+//! [RegistrationRequest], [RegistrationResponse], and [RegistrationUpload]. A successful execution of the registration protocol results in the
+//! server producing a password file corresponding to the password provided by
 //! the client. This password file is typically stored server-side, and retrieved upon future login attempts made by the client.
 //!
-//! In the first step (client registration start), the client chooses a registration password and an optional "pepper", and
-//! runs `ClientRegistration::start` to produce a message `r1`:
+//! ### Client Registration Start
+//! In the first step of registration, the client chooses as input a registration password. The client runs [ClientRegistration::start]
+//! to produce a [ClientRegistrationStartResult], which consists of a [RegistrationRequest] to be sent to the server and
+//! a [ClientRegistration] which must be persisted on the client for the final step of client registration.
 //! ```
 //! # use opaque_ke::{
 //! #   errors::ProtocolError,
-//! #   opaque::{ClientRegistration, ServerRegistration},
-//! #   keypair::{KeyPair, X25519KeyPair, SizedBytes},
+//! #   ServerRegistration,
 //! #   slow_hash::NoOpHash,
 //! # };
 //! # use opaque_ke::ciphersuite::CipherSuite;
 //! # struct Default;
 //! # impl CipherSuite for Default {
 //! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
-//! #     type KeyFormat = opaque_ke::keypair::X25519KeyPair;
 //! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
-//! #     type Hash = sha2::Sha256;
+//! #     type Hash = sha2::Sha512;
 //! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
 //! # }
-//! use rand_core::{OsRng, RngCore};
+//! use opaque_ke::ClientRegistration;
+//! use rand::{rngs::OsRng, RngCore};
 //! let mut client_rng = OsRng;
-//! let (r1, client_state) = ClientRegistration::<Default>::start(
-//!     b"password",
-//!     Some(b"pepper"),
+//! let client_registration_start_result = ClientRegistration::<Default>::start(
 //!     &mut client_rng,
+//!     b"password",
 //! )?;
 //! # Ok::<(), ProtocolError>(())
 //! ```
-//! `r1` is sent to the server, and `client_state` must be persisted on the client for the final step of client
-//! registration.
 //!
-//! In the second step (server registration start), the server takes as input the `r1` message from the client and runs
-//! `ServerRegistration::start` to produce `r2`:
+//! ### Server Registration Start
+//! In the second step of registration, the server takes as input the instance of [RegistrationRequest] from the client, and
+//! the server's public key `server_kp.public()`.
+//! The server runs [ServerRegistration::start] to produce an a [ServerRegistrationStartResult], which consists of
+//! a [RegistrationResponse] to be returned to the client and
+//! a [ServerRegistration] which must be persisted on the server for the final step of server registration.
 //! ```
 //! # use opaque_ke::{
 //! #   errors::ProtocolError,
-//! #   opaque::{ClientRegistration, ServerRegistration},
-//! #   keypair::{KeyPair, X25519KeyPair, SizedBytes},
+//! #   ClientRegistration,
 //! #   slow_hash::NoOpHash,
 //! # };
 //! # use opaque_ke::ciphersuite::CipherSuite;
 //! # struct Default;
 //! # impl CipherSuite for Default {
 //! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
-//! #     type KeyFormat = opaque_ke::keypair::X25519KeyPair;
 //! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
-//! #     type Hash = sha2::Sha256;
+//! #     type Hash = sha2::Sha512;
 //! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
 //! # }
-//! # use rand_core::{OsRng, RngCore};
+//! # use rand::{rngs::OsRng, RngCore};
 //! # let mut client_rng = OsRng;
-//! # let (r1, client_state) = ClientRegistration::<Default>::start(
-//! #     b"password",
-//! #     Some(b"pepper"),
+//! # let client_registration_start_result = ClientRegistration::<Default>::start(
 //! #     &mut client_rng,
+//! #     b"password",
 //! # )?;
+//! use opaque_ke::ServerRegistration;
 //! let mut server_rng = OsRng;
-//! let (r2, server_state) = ServerRegistration::<Default>::start(r1, &mut server_rng)?;
+//! let server_kp = Default::generate_random_keypair(&mut server_rng);
+//! let server_registration_start_result = ServerRegistration::<Default>::start(
+//!     &mut server_rng,
+//!     client_registration_start_result.message,
+//!     server_kp.public(),
+//! )?;
 //! # Ok::<(), ProtocolError>(())
 //! ```
-//! `r2` is returned to the client, and `server_state` must be persisted on the server for the final step of server
-//! registration.
 //!
-//! In the third step (client registration finish), the client takes as input the `r2` message from the server, along
-//! with the server's static public key `server_kp.public()`, and uses `client_state` from the first step to run
-//! `finish` and produce a message `r3` along with the export key `export_key_registration`:
+//! ### Client Registration Finish
+//! In the third step of registration, the client takes as input
+//! a [RegistrationResponse] from the server, and
+//! a [ClientRegistration] from the first step of registration.
+//! The client runs [ClientRegistration::finish] to produce a [ClientRegistrationFinishResult], which consists of a [RegistrationUpload]
+//! to be sent to the server and an `export_key` field which can be used optionally as described in the [Export Key](#export-key) section.
 //! ```
 //! # use opaque_ke::{
 //! #   errors::ProtocolError,
-//! #   opaque::{ClientRegistration, ServerRegistration},
-//! #   keypair::{KeyPair, X25519KeyPair, SizedBytes},
+//! #   ClientRegistration, ClientRegistrationFinishParameters, ServerRegistration,
 //! #   slow_hash::NoOpHash,
 //! # };
 //! # use opaque_ke::ciphersuite::CipherSuite;
 //! # struct Default;
 //! # impl CipherSuite for Default {
 //! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
-//! #     type KeyFormat = opaque_ke::keypair::X25519KeyPair;
 //! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
-//! #     type Hash = sha2::Sha256;
+//! #     type Hash = sha2::Sha512;
 //! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
 //! # }
-//! # use rand_core::{OsRng, RngCore};
+//! # use rand::{rngs::OsRng, RngCore};
 //! # let mut client_rng = OsRng;
-//! # let (r1, client_state) = ClientRegistration::<Default>::start(
-//! #     b"password",
-//! #     Some(b"pepper"),
+//! # let client_registration_start_result = ClientRegistration::<Default>::start(
 //! #     &mut client_rng,
+//! #     b"password",
 //! # )?;
 //! # let mut server_rng = OsRng;
-//! let (r2, server_state) = ServerRegistration::<Default>::start(r1, &mut server_rng)?;
-//! # let server_kp = Default::generate_random_keypair(&mut server_rng)?;
-//! let (r3, export_key_registration) =
-//!     client_state.finish(r2, server_kp.public(), &mut client_rng)?;
+//! # let server_kp = Default::generate_random_keypair(&mut server_rng);
+//! # let server_registration_start_result = ServerRegistration::<Default>::start(&mut server_rng, client_registration_start_result.message, server_kp.public())?;
+//! let client_registration_finish_result = client_registration_start_result.state.finish(
+//!     &mut client_rng,
+//!     server_registration_start_result.message,
+//!     ClientRegistrationFinishParameters::default(),
+//! )?;
 //! # Ok::<(), ProtocolError>(())
 //! ```
-//! `r3` is sent to the server, and the client can optionally use `export_key_registration` for applications that choose to
-//! process user information beyond the OPAQUE functionality (e.g., additional secrets or credentials).
 //!
-//! In the fourth step of registration, the server takes as input the `r3` message from the client and uses
-//! `server_state` from the second step to run `finish` and produce `password_file`:
+//! ### Server Registration Finish
+//! In the fourth step of registration, the server takes as input
+//! a [RegistrationUpload] from the client, and
+//! a [ServerRegistration] from the second step.
+//! The server runs [ServerRegistration::finish] to produce a finalized [ServerRegistration].
+//! At this point, the client can be considered as successfully registered, and the server can invoke
+//! [ServerRegistration::serialize] to store the password file for use during the login protocol.
 //! ```
 //! # use opaque_ke::{
 //! #   errors::ProtocolError,
-//! #   opaque::{ClientRegistration, ServerRegistration},
-//! #   keypair::{KeyPair, X25519KeyPair, SizedBytes},
+//! #   ClientRegistration, ClientRegistrationFinishParameters, ServerRegistration,
 //! #   slow_hash::NoOpHash,
 //! # };
 //! # use opaque_ke::ciphersuite::CipherSuite;
 //! # struct Default;
 //! # impl CipherSuite for Default {
 //! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
-//! #     type KeyFormat = opaque_ke::keypair::X25519KeyPair;
 //! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
-//! #     type Hash = sha2::Sha256;
+//! #     type Hash = sha2::Sha512;
 //! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
 //! # }
-//! # use rand_core::{OsRng, RngCore};
+//! # use rand::{rngs::OsRng, RngCore};
 //! # let mut client_rng = OsRng;
-//! # let (r1, client_state) = ClientRegistration::<Default>::start(
-//! #     b"password",
-//! #     Some(b"pepper"),
+//! # let client_registration_start_result = ClientRegistration::<Default>::start(
 //! #     &mut client_rng,
+//! #     b"password",
 //! # )?;
 //! # let mut server_rng = OsRng;
-//! let (r2, server_state) = ServerRegistration::<Default>::start(r1, &mut server_rng)?;
-//! # let server_kp = Default::generate_random_keypair(&mut server_rng)?;
-//! # let (r3, export_key_registration) = client_state.finish(r2, server_kp.public(), &mut client_rng)?;
-//! let password_file = server_state.finish(r3)?;
+//! # let server_kp = Default::generate_random_keypair(&mut server_rng);
+//! # let server_registration_start_result = ServerRegistration::<Default>::start(&mut server_rng, client_registration_start_result.message, server_kp.public())?;
+//! # let client_registration_finish_result = client_registration_start_result.state.finish(&mut client_rng, server_registration_start_result.message, ClientRegistrationFinishParameters::default())?;
+//! let password_file = server_registration_start_result.state.finish(
+//!     client_registration_finish_result.message,
+//! )?;
 //! # Ok::<(), ProtocolError>(())
 //! ```
-//! At this point, the client can be considered as successfully registered, and the server can store
-//! `password_file.to_bytes()` for use during the login protocol.
-//!
 //!
 //! ## Login
-//! The login protocol between a client and server also consists of four steps along with three messages, denoted as
-//! `l1`, `l2`, and `l3`. The server is expected to have access to the a password file corresponding to an output
-//! of the registration phase. The login protocol will execute successfully only if the same tuple combination of
-//! (password, pepper, server public key) is presented as was used in the registration phase that produced the
-//! password file that the server is testing against.
+//! The login protocol between a client and server also consists of four steps along with three messages:
+//! [CredentialRequest], [CredentialResponse], [CredentialFinalization]. The server is expected to have access to the password file
+//! corresponding to an output of the registration phase. The login protocol will execute successfully only if the same password
+//! was used in the registration phase that produced the password file that the server is testing against.
 //!
-//! In the first step (client login start), the client chooses a registration password and an optional "pepper", and runs
-//! `ClientLogin::start` to produce a message `l1`:
+//! ### Client Login Start
+//! In the first step of login, the client chooses as input a login password.
+//! The client runs [ClientLogin::start] to produce an output consisting of
+//! a [CredentialRequest] to be sent to the server, and
+//! a [ClientLogin] which must be persisted on the client for the final step of client login.
 //! ```
 //! # use opaque_ke::{
 //! #   errors::ProtocolError,
-//! #   opaque::{ClientRegistration, ServerRegistration, ClientLogin, ServerLogin, LoginThirdMessage},
-//! #   keypair::{KeyPair, X25519KeyPair, SizedBytes},
+//! #   ClientRegistration, ServerRegistration, ServerLogin, CredentialFinalization,
 //! #   slow_hash::NoOpHash,
 //! # };
 //! # use opaque_ke::ciphersuite::CipherSuite;
 //! # struct Default;
 //! # impl CipherSuite for Default {
 //! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
-//! #     type KeyFormat = opaque_ke::keypair::X25519KeyPair;
 //! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
-//! #     type Hash = sha2::Sha256;
+//! #     type Hash = sha2::Sha512;
 //! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
 //! # }
-//! # use rand_core::{OsRng, RngCore};
+//! # use rand::{rngs::OsRng, RngCore};
+//! use opaque_ke::{ClientLogin, ClientLoginStartParameters};
 //! let mut client_rng = OsRng;
-//! let (l1, client_state) = ClientLogin::<Default>::start(
+//! let client_login_start_result = ClientLogin::<Default>::start(
+//!   &mut client_rng,
 //!   b"password",
-//!   Some(b"pepper"),
-//!   &mut client_rng,
+//!   ClientLoginStartParameters::default(),
 //! )?;
 //! # Ok::<(), ProtocolError>(())
 //! ```
-//! `l1` is sent to the server, and `client_state` must be persisted on the client for the final step of client login.
 //!
-//! In the second step (server login start), the server takes as input the `l1` message from the client, the server's
-//! private key `server_kp.private()`, along with a serialized version of the password file, `password_file_bytes`, and
-//! runs `ServerLogin::start` to produce `l2`:
+//! ### Server Login Start
+//! In the second step of login, the server takes as input
+//! a [CredentialRequest] from the client,
+//! the server's private key `server_kp.private()`, and
+//! the password file output from registration.
+//! The server runs [ServerLogin::start] to produce an output consisting of
+//! a [CredentialResponse] which is returned to the client, and
+//! a [ServerLogin] which must be persisted on the server for the final step of login.
 //! ```
 //! # use opaque_ke::{
 //! #   errors::ProtocolError,
-//! #   opaque::{ClientRegistration, ServerRegistration, ClientLogin, ServerLogin, LoginThirdMessage},
-//! #   keypair::{KeyPair, X25519KeyPair, SizedBytes},
+//! #   ClientRegistration, ClientRegistrationFinishParameters, ServerRegistration, ClientLogin, ClientLoginStartParameters, CredentialFinalization,
 //! #   slow_hash::NoOpHash,
 //! # };
 //! # use opaque_ke::ciphersuite::CipherSuite;
 //! # struct Default;
 //! # impl CipherSuite for Default {
 //! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
-//! #     type KeyFormat = opaque_ke::keypair::X25519KeyPair;
 //! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
-//! #     type Hash = sha2::Sha256;
+//! #     type Hash = sha2::Sha512;
 //! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
 //! # }
-//! # use rand_core::{OsRng, RngCore};
+//! # use rand::{rngs::OsRng, RngCore};
 //! # let mut client_rng = OsRng;
-//! # let (r1, client_state) = ClientRegistration::<Default>::start(
-//! #     b"password",
-//! #     Some(b"pepper"),
+//! # let client_registration_start_result = ClientRegistration::<Default>::start(
 //! #     &mut client_rng,
+//! #     b"password",
 //! # )?;
 //! # let mut server_rng = OsRng;
-//! let (r2, server_state) = ServerRegistration::<Default>::start(r1, &mut server_rng)?;
-//! # let server_kp = Default::generate_random_keypair(&mut server_rng)?;
-//! # let (r3, export_key_registration) = client_state.finish(r2, server_kp.public(), &mut client_rng)?;
-//! # let password_file_bytes = server_state.finish(r3)?.to_bytes();
-//! # let (l1, client_state) = ClientLogin::<Default>::start(
-//! #   b"password",
-//! #   Some(b"pepper"),
+//! # let server_kp = Default::generate_random_keypair(&mut server_rng);
+//! # let server_registration_start_result = ServerRegistration::<Default>::start(&mut server_rng, client_registration_start_result.message, server_kp.public())?;
+//! # let client_registration_finish_result = client_registration_start_result.state.finish(&mut client_rng, server_registration_start_result.message, ClientRegistrationFinishParameters::default())?;
+//! # let password_file_bytes = server_registration_start_result.state.finish(client_registration_finish_result.message)?.serialize();
+//! # let client_login_start_result = ClientLogin::<Default>::start(
 //! #   &mut client_rng,
+//! #   b"password",
+//! #   ClientLoginStartParameters::default(),
 //! # )?;
-//! use std::convert::TryFrom;
-//! let password_file = ServerRegistration::<Default>::try_from(&password_file_bytes[..])?;
+//! use opaque_ke::{ServerLogin, ServerLoginStartParameters};
+//! let password_file = ServerRegistration::<Default>::deserialize(&password_file_bytes[..])?;
 //! let mut server_rng = OsRng;
-//! let (l2, server_state) =
-//!     ServerLogin::start(password_file, &server_kp.private(), l1, &mut server_rng)?;
-//! # Ok::<(), ProtocolError>(())
-//! ```
-//! `l2` is returned to the client, and `server_state` must be persisted on the server for the final step of server login.
-//!
-//! In the third step (client login finish), the client takes as input the `l2` message from the server, along with the
-//! server's static public key `server_kp.public()`, and uses `client_state` from the first step to run `finish` and produce
-//! a message `l3`, the shared secret `client_shared_secret`, and the export key `export_key_login`:
-//! ```
-//! # use opaque_ke::{
-//! #   errors::ProtocolError,
-//! #   opaque::{ClientRegistration, ServerRegistration, ClientLogin, ServerLogin, LoginThirdMessage},
-//! #   keypair::{KeyPair, X25519KeyPair, SizedBytes},
-//! #   slow_hash::NoOpHash,
-//! # };
-//! # use opaque_ke::ciphersuite::CipherSuite;
-//! # struct Default;
-//! # impl CipherSuite for Default {
-//! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
-//! #     type KeyFormat = opaque_ke::keypair::X25519KeyPair;
-//! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
-//! #     type Hash = sha2::Sha256;
-//! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
-//! # }
-//! # use rand_core::{OsRng, RngCore};
-//! # let mut client_rng = OsRng;
-//! # let (r1, client_state) = ClientRegistration::<Default>::start(
-//! #     b"password",
-//! #     Some(b"pepper"),
-//! #     &mut client_rng,
-//! # )?;
-//! # let mut server_rng = OsRng;
-//! let (r2, server_state) = ServerRegistration::<Default>::start(r1, &mut server_rng)?;
-//! # let server_kp = Default::generate_random_keypair(&mut server_rng)?;
-//! # let (r3, export_key_registration) = client_state.finish(r2, server_kp.public(), &mut client_rng)?;
-//! # let password_file_bytes = server_state.finish(r3)?.to_bytes();
-//! # let (l1, client_state) = ClientLogin::<Default>::start(
-//! #   b"password",
-//! #   Some(b"pepper"),
-//! #   &mut client_rng,
-//! # )?;
-//! # use std::convert::TryFrom;
-//! # let password_file =
-//! #   ServerRegistration::<Default>::try_from(
-//! #     &password_file_bytes[..],
-//! #   )?;
-//! # let (l2, server_state) =
-//! #     ServerLogin::start(password_file, &server_kp.private(), l1, &mut server_rng)?;
-//! let (l3, client_shared_secret, export_key_login) = client_state.finish(
-//!   l2,
-//!   &server_kp.public(),
-//!   &mut client_rng,
+//! let server_login_start_result = ServerLogin::start(
+//!     &mut server_rng,
+//!     password_file,
+//!     &server_kp.private(),
+//!     client_login_start_result.message,
+//!     ServerLoginStartParameters::default(),
 //! )?;
-//! assert_eq!(export_key_registration, export_key_login);
 //! # Ok::<(), ProtocolError>(())
 //! ```
-//! Note that if the client supplies a tuple (password, pepper, server public key) that does not match the tuple
-//! used to create the password file, then at this point the `finish` algorithm outputs the error `InvalidLoginError`.
 //!
-//! If `finish` completes successfully, then `l3` is sent to the server, and (similarly to registration) the client
-//! can use `export_key_login` for applications that can take advantage of the fact that this key is identical to
-//! `export_key_registration`.
-//!
-//! In the fourth step of login, the server takes as input the `l3` message from the client and uses `server_state` from
-//! the second step to run `finish`:
+//! ### Client Login Finish
+//! In the third step of login, the client takes as input a [CredentialResponse] from the server.
+//! The client runs [ClientLogin::finish] and produces an output consisting of
+//! a [CredentialFinalization] to be sent to the server to complete the protocol,
+//! the `session_key` sequence of bytes which will match the server's session key upon a successful login.
 //! ```
 //! # use opaque_ke::{
 //! #   errors::ProtocolError,
-//! #   opaque::{ClientRegistration, ServerRegistration, ClientLogin, ServerLogin, LoginThirdMessage},
-//! #   keypair::{KeyPair, X25519KeyPair, SizedBytes},
+//! #   ClientRegistration, ClientRegistrationFinishParameters, ServerRegistration, ClientLogin, ClientLoginStartParameters, ClientLoginFinishParameters, ServerLogin, ServerLoginStartParameters, CredentialFinalization,
 //! #   slow_hash::NoOpHash,
 //! # };
 //! # use opaque_ke::ciphersuite::CipherSuite;
 //! # struct Default;
 //! # impl CipherSuite for Default {
 //! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
-//! #     type KeyFormat = opaque_ke::keypair::X25519KeyPair;
 //! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
-//! #     type Hash = sha2::Sha256;
+//! #     type Hash = sha2::Sha512;
 //! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
 //! # }
-//! # use rand_core::{OsRng, RngCore};
+//! # use rand::{rngs::OsRng, RngCore};
 //! # let mut client_rng = OsRng;
-//! # let (r1, client_state) = ClientRegistration::<Default>::start(
-//! #     b"password",
-//! #     Some(b"pepper"),
+//! # let client_registration_start_result = ClientRegistration::<Default>::start(
 //! #     &mut client_rng,
+//! #     b"password",
 //! # )?;
 //! # let mut server_rng = OsRng;
-//! let (r2, server_state) = ServerRegistration::<Default>::start(r1, &mut server_rng)?;
-//! # let server_kp = Default::generate_random_keypair(&mut server_rng)?;
-//! # let (r3, export_key) = client_state.finish(r2, server_kp.public(), &mut client_rng)?;
-//! # let password_file_bytes = server_state.finish(r3)?.to_bytes();
-//! # let (l1, client_state) = ClientLogin::<Default>::start(
-//! #   b"password",
-//! #   Some(b"pepper"),
-//! #   &mut client_rng,
+//! # let server_kp = Default::generate_random_keypair(&mut server_rng);
+//! # let server_registration_start_result = ServerRegistration::<Default>::start(&mut server_rng, client_registration_start_result.message, server_kp.public())?;
+//! # let client_registration_finish_result = client_registration_start_result.state.finish(&mut client_rng, server_registration_start_result.message, ClientRegistrationFinishParameters::default())?;
+//! # let password_file_bytes = server_registration_start_result.state.finish(client_registration_finish_result.message)?.serialize();
+//! # let client_login_start_result = ClientLogin::<Default>::start(
+//! #     &mut client_rng,
+//! #     b"password",
+//! #     ClientLoginStartParameters::default(),
 //! # )?;
-//! # use std::convert::TryFrom;
 //! # let password_file =
-//! #   ServerRegistration::<Default>::try_from(
+//! #   ServerRegistration::<Default>::deserialize(
 //! #     &password_file_bytes[..],
 //! #   )?;
-//! # let (l2, server_state) =
-//! #     ServerLogin::start(password_file, &server_kp.private(), l1, &mut server_rng)?;
-//! # let (l3, client_shared_secret, export_key) = client_state.finish(
-//! #   l2,
-//! #   &server_kp.public(),
-//! #   &mut client_rng,
-//! # )?;
-//! let server_shared_secret = server_state.finish(l3)?;
-//! assert_eq!(client_shared_secret, server_shared_secret);
+//! # let server_login_start_result =
+//! #     ServerLogin::start(&mut server_rng, password_file, &server_kp.private(), client_login_start_result.message, ServerLoginStartParameters::default())?;
+//! let client_login_finish_result = client_login_start_result.state.finish(
+//!     server_login_start_result.message,
+//!     ClientLoginFinishParameters::default(),
+//! )?;
 //! # Ok::<(), ProtocolError>(())
 //! ```
-//! If the protocol completes successfully, then the server obtains a `server_shared_secret` which is guaranteed to
-//! match `client_shared_secret`. Otherwise, on failure, the `finish` algorithm outputs the error `InvalidLoginError`.
+//!
+//! ### Server Login Finish
+//! In the fourth step of login, the server takes as input a [CredentialFinalization] from the client and runs [ServerLogin::finish] to
+//! produce an output consisting of the `session_key` sequence of bytes which will match the client's session key upon a successful login.
+//! ```
+//! # use opaque_ke::{
+//! #   errors::ProtocolError,
+//! #   ClientRegistration, ClientRegistrationFinishParameters, ServerRegistration, ClientLogin, ClientLoginStartParameters, ClientLoginFinishParameters, ServerLogin, ServerLoginStartParameters, CredentialFinalization,
+//! #   slow_hash::NoOpHash,
+//! # };
+//! # use opaque_ke::ciphersuite::CipherSuite;
+//! # struct Default;
+//! # impl CipherSuite for Default {
+//! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
+//! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
+//! #     type Hash = sha2::Sha512;
+//! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
+//! # }
+//! # use rand::{rngs::OsRng, RngCore};
+//! # let mut client_rng = OsRng;
+//! # let client_registration_start_result = ClientRegistration::<Default>::start(
+//! #     &mut client_rng,
+//! #     b"password",
+//! # )?;
+//! # let mut server_rng = OsRng;
+//! # let server_kp = Default::generate_random_keypair(&mut server_rng);
+//! # let server_registration_start_result = ServerRegistration::<Default>::start(&mut server_rng, client_registration_start_result.message, server_kp.public())?;
+//! # let client_registration_finish_result = client_registration_start_result.state.finish(&mut client_rng, server_registration_start_result.message, ClientRegistrationFinishParameters::default())?;
+//! # let password_file_bytes = server_registration_start_result.state.finish(client_registration_finish_result.message)?.serialize();
+//! # let client_login_start_result = ClientLogin::<Default>::start(
+//! #   &mut client_rng,
+//! #   b"password",
+//! #   ClientLoginStartParameters::default(),
+//! # )?;
+//! # let password_file =
+//! #   ServerRegistration::<Default>::deserialize(
+//! #     &password_file_bytes[..],
+//! #   )?;
+//! # let server_login_start_result =
+//! #     ServerLogin::start(&mut server_rng, password_file, &server_kp.private(), client_login_start_result.message, ServerLoginStartParameters::default())?;
+//! # let client_login_finish_result = client_login_start_result.state.finish(
+//! #   server_login_start_result.message,
+//! #   ClientLoginFinishParameters::default(),
+//! # )?;
+//! let server_login_finish_result = server_login_start_result.state.finish(
+//!     client_login_finish_result.message,
+//! )?;
+//!
+//! assert_eq!(
+//!    client_login_finish_result.session_key,
+//!    server_login_finish_result.session_key,
+//! );
+//! # Ok::<(), ProtocolError>(())
+//! ```
+//! If the protocol completes successfully, then the server obtains a `server_login_finish_result.session_key` which is guaranteed to
+//! match `client_login_finish_result.session_key` (see the [Session Key](#session-key) section).
+//! Otherwise, on failure, the [ServerLogin::finish] algorithm outputs the error [InvalidLoginError](errors::PakeError::InvalidLoginError).
+//!
+//! # Advanced Usage
+//!
+//! This implementation offers support for several optional features of OPAQUE, described below. They are not critical to the
+//! execution of the main protocol, but can provide additional security benefits which can be suitable for various applications that rely on
+//! OPAQUE for authentication.
+//!
+//! ## Session Key
+//!
+//! Upon a successful completion of the OPAQUE protocol (the client runs login with the same password used during registration),
+//! the client and server have access to a session key, which is a pseudorandomly distributed 32-byte string which only the client
+//! and server know. Multiple login runs using the same password for the same client will produce different session keys, distributed
+//! as uniformly random strings. Thus, the session key can be used to establish a secure channel between the client and server.
+//!
+//! The session key can be accessed from the `session_key` field of [ClientLoginFinishResult] and [ServerLoginFinishResult]. See
+//! the combination of [Client Login Finish](#client-login-finish) and [Server Login Finish](#server-login-finish) for example usage.
+//!
+//! ## Checking Server Consistency
+//!
+//! A [ClientLoginFinishResult] contains the `server_s_pk` field, which is represents the static public key of the server that is established
+//! during the setup phase. This can be used by the client to verify the authenticity of the server it engages with during the login phase. In particular,
+//! the client can check that the static public key of the server supplied during registration matches this field during login.
+//! ```
+//! # use opaque_ke::{
+//! #   errors::ProtocolError,
+//! #   ClientRegistration, ClientRegistrationFinishParameters, ServerRegistration, ClientLogin, ClientLoginStartParameters, ClientLoginFinishParameters, ServerLogin, ServerLoginStartParameters, CredentialFinalization,
+//! #   slow_hash::NoOpHash,
+//! # };
+//! # use opaque_ke::ciphersuite::CipherSuite;
+//! # struct Default;
+//! # impl CipherSuite for Default {
+//! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
+//! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
+//! #     type Hash = sha2::Sha512;
+//! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
+//! # }
+//! # use rand::{rngs::OsRng, RngCore};
+//! # let mut client_rng = OsRng;
+//! # let client_registration_start_result = ClientRegistration::<Default>::start(
+//! #     &mut client_rng,
+//! #     b"password",
+//! # )?;
+//! # let mut server_rng = OsRng;
+//! // During setup, server generates its static keypair
+//! let server_kp = Default::generate_random_keypair(&mut server_rng);
+//! # let server_registration_start_result = ServerRegistration::<Default>::start(&mut server_rng, client_registration_start_result.message, server_kp.public())?;
+//!
+//! // During setup or registration, the server transmits its static public key to the client
+//! let server_s_pk = server_kp.public(); // obtained from the server
+//! # let client_registration_finish_result = client_registration_start_result.state.finish(&mut client_rng, server_registration_start_result.message, ClientRegistrationFinishParameters::default())?;
+//! # let password_file_bytes = server_registration_start_result.state.finish(client_registration_finish_result.message)?.serialize();
+//! # let client_login_start_result = ClientLogin::<Default>::start(
+//! #     &mut client_rng,
+//! #     b"password",
+//! #     ClientLoginStartParameters::default(),
+//! # )?;
+//! # let password_file =
+//! #   ServerRegistration::<Default>::deserialize(
+//! #     &password_file_bytes[..],
+//! #   )?;
+//! # let server_login_start_result =
+//! #     ServerLogin::start(&mut server_rng, password_file, &server_kp.private(), client_login_start_result.message, ServerLoginStartParameters::default())?;
+//!
+//! // And then later, during login...
+//! let client_login_finish_result = client_login_start_result.state.finish(
+//!     server_login_start_result.message,
+//!     ClientLoginFinishParameters::default(),
+//! )?;
+//!
+//! // Check that the server's static public key matches what was obtained during
+//! // setup or registration
+//! assert_eq!(
+//!     &client_login_finish_result.server_s_pk,
+//!     server_s_pk,
+//! );
+//! # Ok::<(), ProtocolError>(())
+//! ```
+//!
+//! Note that without this check over the consistency of the server's static public key, a malicious actor could impersonate the registration server if it were able to copy the password
+//! file output during registration! Therefore, it is recommended to perform the following check in the application layer if the client can obtain a copy of the server's static
+//! public key beforehand.
+//!
+//!
+//! ## Export Key
+//!
+//! The export key is a pseudorandomly distributed 32-byte string output by both the
+//! [Client Registration Finish](#client-registration-finish) and [Client Login Finish](#client-login-finish) steps.
+//! The same export key string will be output by both functions only if the exact same password is passed to [ClientRegistration::start] and [ClientLogin::start].
+//!
+//! The export key retains as much secrecy as the password itself, and is similarly derived through an evaluation of the slow hashing function. Hence, only the parties which
+//! know the password the client uses during registration and login can recover this secret, as it is never exposed to the server. As a result, the export key
+//! can be used (separately from the OPAQUE protocol) to provide confidentiality and integrity to other data which only the client should be able to process.
+//! For instance, if the server is expected to maintain any client-side secrets which require a password to access, then this export key can be used to encrypt
+//! these secrets so that they remain hidden from the server (see [examples/digital_locker.rs](https://github.com/novifinancial/opaque-ke/blob/master/examples/digital_locker.rs)
+//! for a working example).
+//!
+//! You can access the export key from the `export_key` field of [ClientRegistrationFinishResult] and [ClientLoginFinishResult].
+//!
+//! ```
+//! # use opaque_ke::{
+//! #   errors::ProtocolError,
+//! #   ClientRegistration, ClientRegistrationFinishParameters, ServerRegistration, ClientLogin, ClientLoginStartParameters, ClientLoginFinishParameters, ServerLogin, ServerLoginStartParameters, CredentialFinalization,
+//! #   slow_hash::NoOpHash,
+//! # };
+//! # use opaque_ke::ciphersuite::CipherSuite;
+//! # struct Default;
+//! # impl CipherSuite for Default {
+//! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
+//! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
+//! #     type Hash = sha2::Sha512;
+//! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
+//! # }
+//! # use rand::{rngs::OsRng, RngCore};
+//! # let mut client_rng = OsRng;
+//! # let client_registration_start_result = ClientRegistration::<Default>::start(
+//! #     &mut client_rng,
+//! #     b"password",
+//! # )?;
+//! # let mut server_rng = OsRng;
+//! # let server_kp = Default::generate_random_keypair(&mut server_rng);
+//! # let server_registration_start_result = ServerRegistration::<Default>::start(&mut server_rng, client_registration_start_result.message, server_kp.public())?;
+//! // During registration...
+//! let client_registration_finish_result = client_registration_start_result.state.finish(
+//!     &mut client_rng,
+//!     server_registration_start_result.message,
+//!     ClientRegistrationFinishParameters::default()
+//! )?;
+//! # let password_file_bytes = server_registration_start_result.state.finish(client_registration_finish_result.message)?.serialize();
+//! # let client_login_start_result = ClientLogin::<Default>::start(
+//! #     &mut client_rng,
+//! #     b"password",
+//! #     ClientLoginStartParameters::default(),
+//! # )?;
+//! # let password_file =
+//! #   ServerRegistration::<Default>::deserialize(
+//! #     &password_file_bytes[..],
+//! #   )?;
+//! # let server_login_start_result =
+//! #     ServerLogin::start(&mut server_rng, password_file, &server_kp.private(), client_login_start_result.message, ServerLoginStartParameters::default())?;
+//!
+//! // And then later, during login...
+//! let client_login_finish_result = client_login_start_result.state.finish(
+//!     server_login_start_result.message,
+//!     ClientLoginFinishParameters::default(),
+//! )?;
+//!
+//! assert_eq!(
+//!     client_registration_finish_result.export_key,
+//!     client_login_finish_result.export_key,
+//! );
+//! # Ok::<(), ProtocolError>(())
+//! ```
+//!
+//! ## Custom Identifiers
+//!
+//! Typically when applications use OPAQUE to authenticate a client to a server, the client has a registered "username" which is sent to the server to
+//! identify the corresponding password file established during registration. The server may also have an identifier corresponding to an entity (e.g. facebook.com).
+//! By default, neither of these public identifiers need to be supplied to the OPAQUE protocol.
+//!
+//! But, for applications that wish to cryptographically bind these identities to
+//! the registered password file as well as the session key output by the login phase, these custom identifiers can be specified through
+//! [ClientRegistrationFinishParameters::WithIdentifiers] in [Client Registration Finish](#client-registration-finish):
+//! ```
+//! # use opaque_ke::{
+//! #   errors::ProtocolError,
+//! #   ClientRegistration, ClientRegistrationFinishParameters, ServerRegistration,
+//! #   slow_hash::NoOpHash,
+//! # };
+//! # use opaque_ke::ciphersuite::CipherSuite;
+//! # struct Default;
+//! # impl CipherSuite for Default {
+//! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
+//! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
+//! #     type Hash = sha2::Sha512;
+//! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
+//! # }
+//! # use rand::{rngs::OsRng, RngCore};
+//! # let mut client_rng = OsRng;
+//! # let client_registration_start_result = ClientRegistration::<Default>::start(
+//! #     &mut client_rng,
+//! #     b"password",
+//! # )?;
+//! # let mut server_rng = OsRng;
+//! # let server_kp = Default::generate_random_keypair(&mut server_rng);
+//! # let server_registration_start_result = ServerRegistration::<Default>::start(&mut server_rng, client_registration_start_result.message, server_kp.public())?;
+//! let client_registration_finish_result = client_registration_start_result.state.finish(
+//!     &mut client_rng,
+//!     server_registration_start_result.message,
+//!     ClientRegistrationFinishParameters::WithIdentifiers(
+//!         b"username".to_vec(),
+//!         b"facebook.com".to_vec(),
+//!     ),
+//! )?;
+//! # Ok::<(), ProtocolError>(())
+//! ```
+//!
+//! The same identifiers must also be supplied using [ServerLoginStartParameters::WithIdentifiers] in [Server Login Start](#server-login-start):
+//! ```
+//! # use opaque_ke::{
+//! #   errors::ProtocolError,
+//! #   ClientRegistration, ClientRegistrationFinishParameters, ServerRegistration, ClientLogin, ClientLoginStartParameters, CredentialFinalization,
+//! #   slow_hash::NoOpHash,
+//! # };
+//! # use opaque_ke::ciphersuite::CipherSuite;
+//! # struct Default;
+//! # impl CipherSuite for Default {
+//! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
+//! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
+//! #     type Hash = sha2::Sha512;
+//! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
+//! # }
+//! # use rand::{rngs::OsRng, RngCore};
+//! # let mut client_rng = OsRng;
+//! # let client_registration_start_result = ClientRegistration::<Default>::start(
+//! #     &mut client_rng,
+//! #     b"password",
+//! # )?;
+//! # let mut server_rng = OsRng;
+//! # let server_kp = Default::generate_random_keypair(&mut server_rng);
+//! # let server_registration_start_result = ServerRegistration::<Default>::start(&mut server_rng, client_registration_start_result.message, server_kp.public())?;
+//! # let client_registration_finish_result = client_registration_start_result.state.finish(&mut client_rng, server_registration_start_result.message, ClientRegistrationFinishParameters::WithIdentifiers(b"username".to_vec(), b"facebook.com".to_vec()))?;
+//! # let password_file_bytes = server_registration_start_result.state.finish(client_registration_finish_result.message)?.serialize();
+//! # let client_login_start_result = ClientLogin::<Default>::start(
+//! #   &mut client_rng,
+//! #   b"password",
+//! #   ClientLoginStartParameters::default(),
+//! # )?;
+//! # use opaque_ke::{ServerLogin, ServerLoginStartParameters};
+//! # let password_file = ServerRegistration::<Default>::deserialize(&password_file_bytes[..])?;
+//! # let mut server_rng = OsRng;
+//! let server_login_start_result = ServerLogin::start(
+//!     &mut server_rng,
+//!     password_file,
+//!     &server_kp.private(),
+//!     client_login_start_result.message,
+//!     ServerLoginStartParameters::WithIdentifiers(
+//!         b"username".to_vec(),
+//!         b"facebook.com".to_vec(),
+//!     ),
+//! )?;
+//! # Ok::<(), ProtocolError>(())
+//! ```
+//!
+//! as well as [ClientLoginFinishParameters::WithIdentifiers] in [Client Login Finish](#client-login-finish):
+//! ```
+//! # use opaque_ke::{
+//! #   errors::ProtocolError,
+//! #   ClientRegistration, ClientRegistrationFinishParameters, ServerRegistration, ClientLogin, ClientLoginStartParameters, ClientLoginFinishParameters, ServerLogin, ServerLoginStartParameters, CredentialFinalization,
+//! #   slow_hash::NoOpHash,
+//! # };
+//! # use opaque_ke::ciphersuite::CipherSuite;
+//! # struct Default;
+//! # impl CipherSuite for Default {
+//! #     type Group = curve25519_dalek::ristretto::RistrettoPoint;
+//! #     type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDH;
+//! #     type Hash = sha2::Sha512;
+//! #     type SlowHash = opaque_ke::slow_hash::NoOpHash;
+//! # }
+//! # use rand::{rngs::OsRng, RngCore};
+//! # let mut client_rng = OsRng;
+//! # let client_registration_start_result = ClientRegistration::<Default>::start(
+//! #     &mut client_rng,
+//! #     b"password",
+//! # )?;
+//! # let mut server_rng = OsRng;
+//! # let server_kp = Default::generate_random_keypair(&mut server_rng);
+//! # let server_registration_start_result = ServerRegistration::<Default>::start(&mut server_rng, client_registration_start_result.message, server_kp.public())?;
+//! # let client_registration_finish_result = client_registration_start_result.state.finish(&mut client_rng, server_registration_start_result.message, ClientRegistrationFinishParameters::WithIdentifiers(b"username".to_vec(), b"facebook.com".to_vec()))?;
+//! # let password_file_bytes = server_registration_start_result.state.finish(client_registration_finish_result.message)?.serialize();
+//! # let client_login_start_result = ClientLogin::<Default>::start(
+//! #     &mut client_rng,
+//! #     b"password",
+//! #     ClientLoginStartParameters::default(),
+//! # )?;
+//! # let password_file =
+//! #   ServerRegistration::<Default>::deserialize(
+//! #     &password_file_bytes[..],
+//! #   )?;
+//! # let server_login_start_result =
+//! #     ServerLogin::start(&mut server_rng, password_file, &server_kp.private(), client_login_start_result.message, ServerLoginStartParameters::WithIdentifiers(b"username".to_vec(), b"facebook.com".to_vec()))?;
+//! let client_login_finish_result = client_login_start_result.state.finish(
+//!     server_login_start_result.message,
+//!     ClientLoginFinishParameters::WithIdentifiers(
+//!         b"username".to_vec(),
+//!         b"facebook.com".to_vec(),
+//!     ),
+//! )?;
+//! # Ok::<(), ProtocolError>(())
+//! ```
+//! Failing to supply the same pair of custom identifiers in any of the three steps above will result in an error in attempting to complete
+//! the protocol!
+//!
+//! ## Key Exchange Additional Data
+//!
+//! A key exchange protocol typically supports the passing of data between the two parties before the exchange is complete, so as to bind the integrity
+//! and/or confidentiality of application-specific data to the security of the key exchange. During the login phase, the client and server can pass
+//! additional data alongside the first two messages of the protocol, with confidential data being supported for the second message.
+//!
+//! The following three messages support passing of additional data:
+//! - The first login message, where the client can populate [ClientLoginStartParameters::WithInfo] with plaintext additional data, and
+//! the server can retrieve using the `plain_info` field of [ServerLoginStartResult].
+//! - The second login message, where the server can populate [ServerLoginStartParameters::WithInfo] with confidential additional data,
+//! and the client can retrieve using the `confidential_info` field of [ClientLoginFinishResult].
+//!
+//! For the second login message, the `WithInfoAndIdentifiers` variant can be used to specify these fields in addition to
+//! [custom identifiers](#custom-identifiers), with the ordering of the fields as `WithInfoAndIdentifiers(confidential_info, username, server_name)`.
+//!
 //!
 
 #![cfg_attr(not(feature = "bench"), deny(missing_docs))]
@@ -407,13 +713,14 @@ compile_error!(
 pub mod errors;
 
 // High-level API
-pub mod opaque;
+mod opaque;
+
+mod messages;
 
 pub mod ciphersuite;
 mod envelope;
-mod hash;
+pub mod hash;
 
-mod elligator;
 pub mod group;
 
 pub mod map_to_curve;
@@ -428,5 +735,26 @@ mod oprf;
 
 pub mod slow_hash;
 
+mod serialization;
+
 #[cfg(test)]
 mod tests;
+
+// Exports
+
+pub use rand;
+
+pub use crate::messages::{
+    CredentialFinalization, CredentialRequest, CredentialResponse, RegistrationRequest,
+    RegistrationResponse, RegistrationUpload,
+};
+pub use crate::opaque::{ClientLogin, ClientRegistration, ServerLogin, ServerRegistration};
+pub use crate::opaque::{
+    ClientLoginFinishParameters, ClientLoginStartParameters, ClientRegistrationFinishParameters,
+    ServerLoginStartParameters,
+};
+pub use crate::opaque::{
+    ClientLoginFinishResult, ClientLoginStartResult, ClientRegistrationFinishResult,
+    ClientRegistrationStartResult, ServerLoginFinishResult, ServerLoginStartResult,
+    ServerRegistrationStartResult,
+};

src/map_to_curve.rs

@@ -6,29 +6,220 @@
 //! Defines the GroupWithMapToCurve trait to specify how to map a password to a
 //! curve point
 
+use crate::errors::InternalPakeError;
 use crate::group::Group;
-use curve25519_dalek::{edwards::EdwardsPoint, ristretto::RistrettoPoint};
-
+use crate::hash::Hash;
+use crate::serialization::i2osp;
+use curve25519_dalek::ristretto::RistrettoPoint;
+use digest::{BlockInput, Digest};
+use generic_array::typenum::Unsigned;
 use generic_array::GenericArray;
-use hkdf::Hkdf;
-use sha2::{Sha256, Sha512};
 
 /// A subtrait of Group specifying how to hash a password into a point
 pub trait GroupWithMapToCurve: Group {
-    /// transforms a password and optional pepper into a curve point
-    fn map_to_curve(password: &[u8], pepper: Option<&[u8]>) -> Self;
+    /// The ciphersuite identifier as dictated by
+    /// <https://www.ietf.org/archive/id/draft-irtf-cfrg-voprf-05.txt>
+    const SUITE_ID: usize;
+
+    /// transforms a password and domain separation tag (DST) into a curve point
+    fn map_to_curve<H: Hash>(msg: &[u8], dst: &[u8]) -> Result<Self, InternalPakeError>;
+
+    /// Generates the contextString parameter as defined in
+    /// <https://www.ietf.org/archive/id/draft-irtf-cfrg-voprf-05.txt>
+    fn get_context_string(mode: u8) -> Vec<u8> {
+        [i2osp(mode as usize, 1), i2osp(Self::SUITE_ID, 2)].concat()
+    }
 }
 
 impl GroupWithMapToCurve for RistrettoPoint {
-    fn map_to_curve(password: &[u8], pepper: Option<&[u8]>) -> Self {
-        let (hashed_input, _) = Hkdf::<Sha512>::extract(pepper, password);
-        <Self as Group>::hash_to_curve(GenericArray::from_slice(&hashed_input))
+    const SUITE_ID: usize = 0x0001;
+
+    // Implements the hash_to_ristretto255() function from
+    // https://www.ietf.org/archive/id/draft-irtf-cfrg-hash-to-curve-10.txt
+    fn map_to_curve<H: Hash>(msg: &[u8], dst: &[u8]) -> Result<Self, InternalPakeError> {
+        let uniform_bytes =
+            expand_message_xmd::<H>(msg, dst, <H as Digest>::OutputSize::to_usize())?;
+        Ok(<Self as Group>::hash_to_curve(
+            &GenericArray::clone_from_slice(&uniform_bytes[..]),
+        ))
     }
 }
 
-impl GroupWithMapToCurve for EdwardsPoint {
-    fn map_to_curve(password: &[u8], pepper: Option<&[u8]>) -> Self {
-        let (hashed_input, _) = Hkdf::<Sha256>::extract(pepper, password);
-        <Self as Group>::hash_to_curve(GenericArray::from_slice(&hashed_input))
+// Computes ceil(x / y)
+fn div_ceil(x: usize, y: usize) -> usize {
+    let additive = (x % y != 0) as usize;
+    x / y + additive
+}
+
+fn xor(x: &[u8], y: &[u8]) -> Result<Vec<u8>, InternalPakeError> {
+    if x.len() != y.len() {
+        return Err(InternalPakeError::HashToCurveError);
+    }
+
+    Ok(x.iter().zip(y).map(|(&x1, &x2)| x1 ^ x2).collect())
+}
+
+// Corresponds to the expand_message_xmd() function defined in
+// https://www.ietf.org/archive/id/draft-irtf-cfrg-hash-to-curve-10.txt
+pub(crate) fn expand_message_xmd<H: Hash>(
+    msg: &[u8],
+    dst: &[u8],
+    len_in_bytes: usize,
+) -> Result<Vec<u8>, InternalPakeError> {
+    let b_in_bytes = <H as Digest>::OutputSize::to_usize();
+    let r_in_bytes = <H as BlockInput>::BlockSize::to_usize();
+
+    let ell = div_ceil(len_in_bytes, b_in_bytes);
+    if ell > 255 {
+        return Err(InternalPakeError::HashToCurveError);
+    }
+    let dst_prime = [dst, &i2osp(dst.len(), 1)].concat();
+    let z_pad = i2osp(0, r_in_bytes);
+    let l_i_b_str = i2osp(len_in_bytes, 2);
+    let msg_prime = [&z_pad, msg, &l_i_b_str, &i2osp(0, 1), &dst_prime].concat();
+
+    let mut b: Vec<Vec<u8>> = vec![H::digest(&msg_prime).to_vec()]; // b[0]
+
+    let mut h = H::new();
+    h.update(&b[0]);
+    h.update(&i2osp(1, 1));
+    h.update(&dst_prime);
+    b.push(h.finalize_reset().to_vec()); // b[1]
+
+    let mut uniform_bytes: Vec<u8> = Vec::new();
+    uniform_bytes.extend_from_slice(&b[1]);
+
+    for i in 2..(ell + 1) {
+        h.update(xor(&b[0], &b[i - 1])?);
+        h.update(&i2osp(i, 1));
+        h.update(&dst_prime);
+        b.push(h.finalize_reset().to_vec()); // b[i]
+        uniform_bytes.extend_from_slice(&b[i]);
+    }
+
+    Ok(uniform_bytes[..len_in_bytes].to_vec())
+}
+
+#[cfg(test)]
+mod tests {
+
+    struct Params {
+        msg: &'static str,
+        len_in_bytes: usize,
+        uniform_bytes: &'static str,
+    }
+
+    #[test]
+    fn test_expand_message_xmd() {
+        // Test vectors taken from Section K.1 of https://www.ietf.org/archive/id/draft-irtf-cfrg-hash-to-curve-10.txt
+        let test_vectors: Vec<Params> = vec![
+            Params {
+                msg: "",
+                len_in_bytes: 0x20,
+                uniform_bytes: "f659819a6473c1835b25ea59e3d38914c98b374f0970b7e4c\
+                92181df928fca88",
+            },
+            Params {
+                msg: "abc",
+                len_in_bytes: 0x20,
+                uniform_bytes: "1c38f7c211ef233367b2420d04798fa4698080a8901021a79\
+                5a1151775fe4da7",
+            },
+            Params {
+                msg: "abcdef0123456789",
+                len_in_bytes: 0x20,
+                uniform_bytes: "8f7e7b66791f0da0dbb5ec7c22ec637f79758c0a48170bfb7c4611bd304ece89",
+            },
+            Params {
+                msg: "q128_qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq\
+                qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq\
+                qqqqqqqqqqqqqqqqqqqqqqqqq",
+                len_in_bytes: 0x20,
+                uniform_bytes: "72d5aa5ec810370d1f0013c0df2f1d65699494ee2a39f72e\
+                1716b1b964e1c642",
+            },
+            Params {
+                msg: "a512_aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+                len_in_bytes: 0x20,
+                uniform_bytes: "3b8e704fc48336aca4c2a12195b720882f2162a4b7b13a9c\
+                350db46f429b771b",
+            },
+            Params {
+                msg: "",
+                len_in_bytes: 0x80,
+                uniform_bytes: "8bcffd1a3cae24cf9cd7ab85628fd111bb17e3739d3b53f8\
+                9580d217aa79526f1708354a76a402d3569d6a9d19ef3de4d0b991\
+                e4f54b9f20dcde9b95a66824cbdf6c1a963a1913d43fd7ac443a02\
+                fc5d9d8d77e2071b86ab114a9f34150954a7531da568a1ea8c7608\
+                61c0cde2005afc2c114042ee7b5848f5303f0611cf297f",
+            },
+            Params {
+                msg: "abc",
+                len_in_bytes: 0x80,
+                uniform_bytes: "fe994ec51bdaa821598047b3121c149b364b178606d5e72b\
+                fbb713933acc29c186f316baecf7ea22212f2496ef3f785a27e84a\
+                40d8b299cec56032763eceeff4c61bd1fe65ed81decafff4a31d01\
+                98619c0aa0c6c51fca15520789925e813dcfd318b542f879944127\
+                1f4db9ee3b8092a7a2e8d5b75b73e28fb1ab6b4573c192",
+            },
+            Params {
+                msg: "abcdef0123456789",
+                len_in_bytes: 0x80,
+                uniform_bytes: "c9ec7941811b1e19ce98e21db28d22259354d4d0643e3011\
+                75e2f474e030d32694e9dd5520dde93f3600d8edad94e5c3649030\
+                88a7228cc9eff685d7eaac50d5a5a8229d083b51de4ccc3733917f\
+                4b9535a819b445814890b7029b5de805bf62b33a4dc7e24acdf2c9\
+                24e9fe50d55a6b832c8c84c7f82474b34e48c6d43867be",
+            },
+            Params {
+                msg: "q128_qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq\
+                qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq\
+                qqqqqqqqqqqqqqqqqqqqqqqqq",
+                len_in_bytes: 0x80,
+                uniform_bytes: "48e256ddba722053ba462b2b93351fc966026e6d6db49318\
+                9798181c5f3feea377b5a6f1d8368d7453faef715f9aecb078cd40\
+                2cbd548c0e179c4ed1e4c7e5b048e0a39d31817b5b24f50db58bb3\
+                720fe96ba53db947842120a068816ac05c159bb5266c63658b4f00\
+                0cbf87b1209a225def8ef1dca917bcda79a1e42acd8069",
+            },
+            Params {
+                msg: "a512_aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
+                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+                len_in_bytes: 0x80,
+                uniform_bytes: "396962db47f749ec3b5042ce2452b619607f27fd3939ece2\
+                746a7614fb83a1d097f554df3927b084e55de92c7871430d6b95c2\
+                a13896d8a33bc48587b1f66d21b128a1a8240d5b0c26dfe795a1a8\
+                42a0807bb148b77c2ef82ed4b6c9f7fcb732e7f94466c8b51e52bf\
+                378fba044a31f5cb44583a892f5969dcd73b3fa128816e",
+            },
+        ];
+        let dst = "QUUX-V01-CS02-with-expander";
+
+        for tv in test_vectors {
+            let uniform_bytes = super::expand_message_xmd::<sha2::Sha256>(
+                tv.msg.as_bytes(),
+                dst.as_bytes(),
+                tv.len_in_bytes,
+            )
+            .unwrap();
+            assert_eq!(tv.uniform_bytes, hex::encode(uniform_bytes));
+        }
     }
 }

src/messages.rs

@@ -0,0 +1,250 @@
+// Copyright (c) Facebook, Inc. and its affiliates.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+//! Contains the messages used for OPAQUE
+
+use crate::{
+    ciphersuite::CipherSuite,
+    envelope::Envelope,
+    errors::{
+        utils::{check_slice_size, check_slice_size_atleast},
+        PakeError, ProtocolError,
+    },
+    group::Group,
+    key_exchange::traits::{KeyExchange, ToBytes},
+    keypair::{Key, KeyPair, SizedBytesExt},
+};
+use generic_array::{typenum::Unsigned, GenericArray};
+use generic_bytes::SizedBytes;
+use std::convert::TryFrom;
+
+// Messages
+// =========
+
+/// The message sent by the client to the server, to initiate registration
+pub struct RegistrationRequest<CS: CipherSuite> {
+    /// blinded password information
+    pub(crate) alpha: CS::Group,
+}
+
+impl<CS: CipherSuite> RegistrationRequest<CS> {
+    /// Serialization into bytes
+    pub fn serialize(&self) -> Vec<u8> {
+        self.alpha.to_arr().to_vec()
+    }
+
+    /// Deserialization from bytes
+    pub fn deserialize(input: &[u8]) -> Result<Self, ProtocolError> {
+        let elem_len = <CS::Group as Group>::ElemLen::to_usize();
+        let checked_slice = check_slice_size(&input, elem_len, "first_message_bytes")?;
+        // Check that the message is actually containing an element of the
+        // correct subgroup
+        let arr = GenericArray::from_slice(checked_slice);
+        let alpha = CS::Group::from_element_slice(arr)?;
+        Ok(Self { alpha })
+    }
+}
+
+/// The answer sent by the server to the user, upon reception of the
+/// registration attempt
+pub struct RegistrationResponse<CS: CipherSuite> {
+    /// The server's oprf output
+    pub(crate) beta: CS::Group,
+    /// Server's static public key
+    pub(crate) server_s_pk: Vec<u8>,
+}
+
+impl<CS: CipherSuite> RegistrationResponse<CS> {
+    /// Serialization into bytes
+    pub fn serialize(&self) -> Vec<u8> {
+        [self.beta.to_arr().to_vec(), self.server_s_pk.clone()].concat()
+    }
+
+    /// Deserialization from bytes
+    pub fn deserialize(input: &[u8]) -> Result<Self, ProtocolError> {
+        let elem_len = <CS::Group as Group>::ElemLen::to_usize();
+        let key_len = <Key as SizedBytes>::Len::to_usize();
+        let checked_slice =
+            check_slice_size(&input, elem_len + key_len, "registration_response_bytes")?;
+
+        // Check that the message is actually containing an element of the
+        // correct subgroup
+        let arr = GenericArray::from_slice(&checked_slice[..elem_len]);
+        let beta = CS::Group::from_element_slice(arr)?;
+
+        Ok(Self {
+            server_s_pk: checked_slice[elem_len..].to_vec(),
+            beta,
+        })
+    }
+}
+
+/// The final message from the client, containing sealed cryptographic
+/// identifiers
+pub struct RegistrationUpload<CS: CipherSuite> {
+    /// The "envelope" generated by the user, containing sealed
+    /// cryptographic identifiers
+    pub(crate) envelope: Envelope<CS::Hash>,
+    /// The user's public key
+    pub(crate) client_s_pk: Key,
+}
+
+impl<CS: CipherSuite> RegistrationUpload<CS> {
+    /// Serialization into bytes
+    pub fn serialize(&self) -> Vec<u8> {
+        [
+            self.client_s_pk.to_arr().to_vec(),
+            self.envelope.serialize(),
+        ]
+        .concat()
+    }
+
+    /// Deserialization from bytes
+    pub fn deserialize(input: &[u8]) -> Result<Self, ProtocolError> {
+        let key_len = <Key as SizedBytes>::Len::to_usize();
+
+        let checked_slice = check_slice_size_atleast(&input, key_len, "registration_upload_bytes")?;
+
+        let (envelope, remainder) = Envelope::<CS::Hash>::deserialize(&checked_slice[key_len..])?;
+
+        if !remainder.is_empty() {
+            return Err(PakeError::SerializationError.into());
+        }
+
+        Ok(Self {
+            envelope,
+            client_s_pk: KeyPair::<CS::Group>::check_public_key(Key::from_bytes(
+                &checked_slice[..key_len],
+            )?)?,
+        })
+    }
+}
+
+/// The message sent by the user to the server, to initiate registration
+pub struct CredentialRequest<CS: CipherSuite> {
+    /// blinded password information
+    pub(crate) alpha: CS::Group,
+    pub(crate) ke1_message: <CS::KeyExchange as KeyExchange<CS::Hash, CS::Group>>::KE1Message,
+}
+
+impl<CS: CipherSuite> CredentialRequest<CS> {
+    /// Serialization into bytes
+    pub fn serialize(&self) -> Vec<u8> {
+        let mut credential_request: Vec<u8> = Vec::new();
+        credential_request.extend_from_slice(&self.alpha.to_arr());
+        credential_request.extend_from_slice(&self.ke1_message.to_bytes());
+        credential_request
+    }
+
+    /// Deserialization from bytes
+    pub fn deserialize(input: &[u8]) -> Result<Self, ProtocolError> {
+        let elem_len = <CS::Group as Group>::ElemLen::to_usize();
+
+        let checked_slice =
+            check_slice_size_atleast(&input, elem_len, "login_first_message_bytes")?;
+
+        // Check that the message is actually containing an element of the
+        // correct subgroup
+        let arr = GenericArray::from_slice(&checked_slice[..elem_len]);
+        let alpha = CS::Group::from_element_slice(arr)?;
+
+        let ke1_message =
+            <CS::KeyExchange as KeyExchange<CS::Hash, CS::Group>>::KE1Message::try_from(
+                &checked_slice[elem_len..],
+            )?;
+
+        Ok(Self { alpha, ke1_message })
+    }
+}
+
+/// The answer sent by the server to the user, upon reception of the
+/// login attempt
+pub struct CredentialResponse<CS: CipherSuite> {
+    /// the server's oprf output
+    pub(crate) beta: CS::Group,
+    pub(crate) server_s_pk: Key,
+    /// the user's sealed information,
+    pub(crate) envelope: Envelope<CS::Hash>,
+    pub(crate) ke2_message: <CS::KeyExchange as KeyExchange<CS::Hash, CS::Group>>::KE2Message,
+}
+
+impl<CS: CipherSuite> CredentialResponse<CS> {
+    /// Serialization into bytes
+    pub fn serialize(&self) -> Vec<u8> {
+        [
+            Self::serialize_without_ke(&self.beta, &self.server_s_pk, &self.envelope),
+            self.ke2_message.to_bytes(),
+        ]
+        .concat()
+    }
+
+    pub(crate) fn serialize_without_ke(
+        beta: &CS::Group,
+        server_s_pk: &Key,
+        envelope: &Envelope<CS::Hash>,
+    ) -> Vec<u8> {
+        [
+            &beta.to_arr(),
+            &server_s_pk.to_arr()[..],
+            &envelope.to_bytes(),
+        ]
+        .concat()
+    }
+
+    /// Deserialization from bytes
+    pub fn deserialize(input: &[u8]) -> Result<Self, ProtocolError> {
+        let elem_len = <CS::Group as Group>::ElemLen::to_usize();
+        let key_len = <Key as SizedBytes>::Len::to_usize();
+        let checked_slice =
+            check_slice_size_atleast(input, elem_len + key_len, "login_second_message_bytes")?;
+
+        // Check that the message is actually containing an element of the
+        // correct subgroup
+        let beta_bytes = &checked_slice[..elem_len];
+        let arr = GenericArray::from_slice(beta_bytes);
+        let beta = CS::Group::from_element_slice(arr)?;
+
+        let unchecked_server_s_pk = Key::from_bytes(&checked_slice[elem_len..elem_len + key_len])?;
+        let server_s_pk = KeyPair::<CS::Group>::check_public_key(unchecked_server_s_pk)?;
+
+        let (envelope, remainder) =
+            Envelope::<CS::Hash>::deserialize(&checked_slice[elem_len + key_len..])?;
+
+        let ke2_message_size = CS::KeyExchange::ke2_message_size();
+        let checked_remainder =
+            check_slice_size_atleast(&remainder, ke2_message_size, "login_second_message_bytes")?;
+        let ke2_message =
+            <CS::KeyExchange as KeyExchange<CS::Hash, CS::Group>>::KE2Message::try_from(
+                &checked_remainder,
+            )?;
+
+        Ok(Self {
+            beta,
+            server_s_pk,
+            envelope,
+            ke2_message,
+        })
+    }
+}
+
+/// The answer sent by the client to the server, upon reception of the
+/// sealed envelope
+pub struct CredentialFinalization<CS: CipherSuite> {
+    pub(crate) ke3_message: <CS::KeyExchange as KeyExchange<CS::Hash, CS::Group>>::KE3Message,
+}
+
+impl<CS: CipherSuite> CredentialFinalization<CS> {
+    /// Serialization into bytes
+    pub fn serialize(&self) -> Vec<u8> {
+        self.ke3_message.to_bytes()
+    }
+
+    /// Deserialization from bytes
+    pub fn deserialize(input: &[u8]) -> Result<Self, ProtocolError> {
+        let ke3_message =
+            <CS::KeyExchange as KeyExchange<CS::Hash, CS::Group>>::KE3Message::try_from(input)?;
+        Ok(Self { ke3_message })
+    }
+}

src/oprf.rs

@@ -5,89 +5,109 @@
 
 use crate::{
     errors::InternalPakeError, group::Group, hash::Hash, map_to_curve::GroupWithMapToCurve,
+    serialization::serialize,
 };
 use digest::Digest;
 use generic_array::GenericArray;
-use hkdf::Hkdf;
-use rand_core::{CryptoRng, RngCore};
+use rand::{CryptoRng, RngCore};
 
-pub struct OprfClientBytes<Grp: Group> {
-    pub alpha: Grp,
-    pub blinding_factor: Grp::Scalar,
+/// Used to store the OPRF input and blinding factor
+pub struct Token<Grp: Group> {
+    pub(crate) data: Vec<u8>,
+    pub(crate) blind: Grp::Scalar,
 }
 
+static STR_VOPRF: &[u8] = b"VOPRF06-HashToGroup-";
+static STR_VOPRF_FINALIZE: &[u8] = b"VOPRF06-Finalize-";
+static MODE_BASE: u8 = 0x00;
+
 /// Computes the first step for the multiplicative blinding version of DH-OPRF. This
 /// message is sent from the client (who holds the input) to the server (who holds the OPRF key).
 /// The client can also pass in an optional "pepper" string to be mixed in with the input through
 /// an HKDF computation.
-pub(crate) fn generate_oprf1<R: RngCore + CryptoRng, G: GroupWithMapToCurve>(
+pub(crate) fn blind<R: RngCore + CryptoRng, G: GroupWithMapToCurve, H: Hash>(
     input: &[u8],
-    pepper: Option<&[u8]>,
     blinding_factor_rng: &mut R,
-) -> Result<OprfClientBytes<G>, InternalPakeError> {
-    let mapped_point = G::map_to_curve(input, pepper);
-    let blinding_factor = G::random_scalar(blinding_factor_rng);
-    let alpha = mapped_point * &blinding_factor;
-    Ok(OprfClientBytes {
-        alpha,
-        blinding_factor,
-    })
+) -> Result<(Token<G>, G), InternalPakeError> {
+    let blind = G::random_scalar(blinding_factor_rng);
+    let dst = [STR_VOPRF, &G::get_context_string(MODE_BASE)].concat();
+    let mapped_point = G::map_to_curve::<H>(input, &dst)?;
+    let blind_token = mapped_point * &blind;
+    Ok((
+        Token {
+            data: input.to_vec(),
+            blind,
+        },
+        blind_token,
+    ))
 }
 
 /// Computes the second step for the multiplicative blinding version of DH-OPRF. This
 /// message is sent from the server (who holds the OPRF key) to the client.
-pub(crate) fn generate_oprf2<G: Group>(
-    point: G,
-    oprf_key: &G::Scalar,
-) -> Result<G, InternalPakeError> {
-    Ok(point * oprf_key)
+pub(crate) fn evaluate<G: Group>(point: G, oprf_key: &G::Scalar) -> G {
+    point * oprf_key
 }
 
 /// Computes the third step for the multiplicative blinding version of DH-OPRF, in which
 /// the client unblinds the server's message.
-pub(crate) fn generate_oprf3<G: Group, H: Hash>(
+pub(crate) fn finalize<G: GroupWithMapToCurve, H: Hash>(
     input: &[u8],
-    point: G,
-    blinding_factor: &G::Scalar,
-) -> Result<GenericArray<u8, <H as Digest>::OutputSize>, InternalPakeError> {
-    let unblinded = point * &G::scalar_invert(&blinding_factor);
-    let ikm: Vec<u8> = [&unblinded.to_arr()[..], input].concat();
-    let (prk, _) = Hkdf::<H>::extract(None, &ikm);
-    Ok(prk)
+    blind: &G::Scalar,
+    evaluated_element: G,
+) -> GenericArray<u8, <H as Digest>::OutputSize> {
+    let unblinded_element = evaluated_element * &G::scalar_invert(blind);
+    finalize_after_unblind::<G, H>(input, unblinded_element)
 }
 
-// Benchmarking shims
-#[cfg(feature = "bench")]
-#[inline]
-pub fn generate_oprf1_shim<R: RngCore + CryptoRng, G: GroupWithMapToCurve>(
+fn finalize_after_unblind<G: GroupWithMapToCurve, H: Hash>(
+    input: &[u8],
+    unblinded_element: G,
+) -> GenericArray<u8, <H as Digest>::OutputSize> {
+    let finalize_dst = [STR_VOPRF_FINALIZE, &G::get_context_string(MODE_BASE)].concat();
+    let hash_input = [
+        serialize(input, 2),
+        serialize(&unblinded_element.to_arr().to_vec(), 2),
+        serialize(&finalize_dst, 2),
+    ]
+    .concat();
+    <H as Digest>::digest(&hash_input)
+}
+
+////////////////////////
+// Benchmarking shims //
+////////////////////////
+
+#[cfg(feature = "bench")]
+#[doc(hidden)]
+#[inline]
+pub fn blind_shim<R: RngCore + CryptoRng, G: GroupWithMapToCurve, H: Hash>(
     input: &[u8],
-    pepper: Option<&[u8]>,
     blinding_factor_rng: &mut R,
-) -> Result<OprfClientBytes<G>, InternalPakeError> {
-    generate_oprf1(input, pepper, blinding_factor_rng)
+) -> Result<(Token<G>, G), InternalPakeError> {
+    blind::<R, G, H>(input, blinding_factor_rng)
 }
 
 #[cfg(feature = "bench")]
+#[doc(hidden)]
 #[inline]
-pub fn generate_oprf2_shim<G: Group>(
-    point: G,
-    oprf_key: &G::Scalar,
-) -> Result<G, InternalPakeError> {
-    generate_oprf2(point, oprf_key)
+pub fn evaluate_shim<G: Group>(point: G, oprf_key: &G::Scalar) -> G {
+    evaluate(point, oprf_key)
 }
 
 #[cfg(feature = "bench")]
+#[doc(hidden)]
 #[inline]
-pub fn generate_oprf3_shim<G: Group, H: Hash>(
-    input: &[u8],
+pub fn finalize_shim<G: GroupWithMapToCurve, H: Hash>(
+    token: &Token<G>,
     point: G,
-    blinding_factor: &G::Scalar,
 ) -> Result<GenericArray<u8, <H as Digest>::OutputSize>, InternalPakeError> {
-    generate_oprf3::<G, H>(input, point, blinding_factor)
+    Ok(finalize::<G, H>(&token.data, &token.blind, point))
 }
 
-// Tests
-// =====
+///////////
+// Tests //
+// ===== //
+///////////
 
 #[cfg(test)]
 mod tests {
@@ -95,41 +115,32 @@ mod tests {
     use crate::group::Group;
     use curve25519_dalek::ristretto::RistrettoPoint;
     use generic_array::{arr, GenericArray};
-    use hkdf::Hkdf;
-    use rand_core::OsRng;
-    use sha2::{Sha256, Sha512};
+    use rand::rngs::OsRng;
+    use sha2::Sha512;
 
-    fn prf(
-        input: &[u8],
-        oprf_key: &[u8; 32],
-    ) -> GenericArray<u8, <RistrettoPoint as Group>::ElemLen> {
-        let (hashed_input, _) = Hkdf::<Sha512>::extract(None, &input);
-        let point = RistrettoPoint::hash_to_curve(GenericArray::from_slice(&hashed_input));
+    fn prf(input: &[u8], oprf_key: &[u8; 32]) -> GenericArray<u8, <Sha512 as Digest>::OutputSize> {
+        let dst = [STR_VOPRF, &RistrettoPoint::get_context_string(MODE_BASE)].concat();
+        let point = RistrettoPoint::map_to_curve::<Sha512>(input, &dst).unwrap();
         let scalar =
             RistrettoPoint::from_scalar_slice(GenericArray::from_slice(&oprf_key[..])).unwrap();
         let res = point * scalar;
-        let ikm: Vec<u8> = [&res.to_arr()[..], &input].concat();
 
-        let (prk, _) = Hkdf::<Sha256>::extract(None, &ikm);
-        prk
+        finalize_after_unblind::<RistrettoPoint, sha2::Sha512>(&input, res)
     }
 
     #[test]
     fn oprf_retrieval() -> Result<(), InternalPakeError> {
         let input = b"hunter2";
         let mut rng = OsRng;
-        let OprfClientBytes {
-            alpha,
-            blinding_factor,
-        } = generate_oprf1::<_, RistrettoPoint>(&input[..], None, &mut rng)?;
-        let salt_bytes = arr![
+        let (token, alpha) = blind::<_, RistrettoPoint, Sha512>(&input[..], &mut rng)?;
+        let oprf_key_bytes = arr![
             u8; 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
             24, 25, 26, 27, 28, 29, 30, 31, 32,
         ];
-        let salt = RistrettoPoint::from_scalar_slice(&salt_bytes)?;
-        let beta = generate_oprf2::<RistrettoPoint>(alpha, &salt)?;
-        let res = generate_oprf3::<RistrettoPoint, sha2::Sha256>(input, beta, &blinding_factor)?;
-        let res2 = prf(&input[..], &salt.as_bytes());
+        let oprf_key = RistrettoPoint::from_scalar_slice(&oprf_key_bytes)?;
+        let beta = evaluate::<RistrettoPoint>(alpha, &oprf_key);
+        let res = finalize::<RistrettoPoint, sha2::Sha512>(&token.data, &token.blind, beta);
+        let res2 = prf(&input[..], &oprf_key.as_bytes());
         assert_eq!(res, res2);
         Ok(())
     }
@@ -139,23 +150,13 @@ mod tests {
         let mut rng = OsRng;
         let mut input = vec![0u8; 64];
         rng.fill_bytes(&mut input);
-        let OprfClientBytes {
-            alpha,
-            blinding_factor,
-        } = generate_oprf1::<_, RistrettoPoint>(&input, None, &mut rng).unwrap();
-        let res = generate_oprf3::<RistrettoPoint, sha2::Sha256>(&input, alpha, &blinding_factor)
-            .unwrap();
+        let (token, alpha) = blind::<_, RistrettoPoint, sha2::Sha512>(&input, &mut rng).unwrap();
+        let res = finalize::<RistrettoPoint, sha2::Sha512>(&token.data, &token.blind, alpha);
 
-        let (hashed_input, _) = Hkdf::<Sha512>::extract(None, &input);
-        let mut bits = [0u8; 64];
-        bits.copy_from_slice(&hashed_input);
+        let dst = [STR_VOPRF, &RistrettoPoint::get_context_string(MODE_BASE)].concat();
+        let point = RistrettoPoint::map_to_curve::<Sha512>(&input, &dst).unwrap();
+        let res2 = finalize_after_unblind::<RistrettoPoint, sha2::Sha512>(&input, point);
 
-        let point = RistrettoPoint::from_uniform_bytes(&bits);
-        let mut ikm: Vec<u8> = Vec::new();
-        ikm.extend_from_slice(&point.to_arr());
-        ikm.extend_from_slice(&input);
-        let (prk, _) = Hkdf::<Sha256>::extract(None, &ikm);
-
-        assert_eq!(res, prk);
+        assert_eq!(res, res2);
     }
 }

src/serialization/mod.rs

@@ -0,0 +1,57 @@
+// Copyright (c) Facebook, Inc. and its affiliates.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+use crate::errors::PakeError;
+
+// Corresponds to the I2OSP() function from RFC8017
+pub(crate) fn i2osp(input: usize, length: usize) -> Vec<u8> {
+    if length <= std::mem::size_of::<usize>() {
+        return (&input.to_be_bytes()[std::mem::size_of::<usize>() - length..]).to_vec();
+    }
+
+    let mut output = vec![0u8; length];
+    output.splice(
+        length - std::mem::size_of::<usize>()..length,
+        input.to_be_bytes().iter().cloned(),
+    );
+    output
+}
+
+// Corresponds to the OS2IP() function from RFC8017
+pub(crate) fn os2ip(input: &[u8]) -> Result<usize, PakeError> {
+    if input.len() > std::mem::size_of::<usize>() {
+        return Err(PakeError::SerializationError);
+    }
+
+    let mut output_array = [0u8; std::mem::size_of::<usize>()];
+    output_array[std::mem::size_of::<usize>() - input.len()..].copy_from_slice(input);
+    Ok(usize::from_be_bytes(output_array))
+}
+
+// Computes I2OSP(len(input), max_bytes) || input
+pub(crate) fn serialize(input: &[u8], max_bytes: usize) -> Vec<u8> {
+    [&i2osp(input.len(), max_bytes), input].concat()
+}
+
+// Tokenizes an input of the format I2OSP(len(input), max_bytes) || input, outputting
+// (input, remainder)
+pub(crate) fn tokenize(input: &[u8], size_bytes: usize) -> Result<(Vec<u8>, Vec<u8>), PakeError> {
+    if size_bytes > std::mem::size_of::<usize>() || input.len() < size_bytes {
+        return Err(PakeError::SerializationError);
+    }
+
+    let size = os2ip(&input[..size_bytes])?;
+    if size_bytes + size > input.len() {
+        return Err(PakeError::SerializationError);
+    }
+
+    Ok((
+        input[size_bytes..size_bytes + size].to_vec(),
+        input[size_bytes + size..].to_vec(),
+    ))
+}
+
+#[cfg(test)]
+mod tests;

src/serialization/tests.rs

@@ -0,0 +1,403 @@
+// Copyright (c) Facebook, Inc. and its affiliates.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+use crate::{
+    ciphersuite::CipherSuite,
+    envelope::{Envelope, InnerEnvelopeMode},
+    group::Group,
+    key_exchange::{
+        traits::{KeyExchange, ToBytes},
+        tripledh::{NonceLen, TripleDH},
+    },
+    opaque::*,
+    serialization::{i2osp, os2ip, serialize},
+    *,
+};
+
+use curve25519_dalek::ristretto::RistrettoPoint;
+use generic_array::typenum::Unsigned;
+use generic_bytes::SizedBytes;
+use proptest::{collection::vec, prelude::*};
+use rand::{rngs::OsRng, RngCore};
+
+use sha2::Digest;
+use std::convert::TryFrom;
+
+struct Default;
+impl CipherSuite for Default {
+    type Group = RistrettoPoint;
+    type KeyExchange = TripleDH;
+    type Hash = sha2::Sha512;
+    type SlowHash = crate::slow_hash::NoOpHash;
+}
+
+const MAX_INFO_LENGTH: usize = 10;
+const MAC_SIZE: usize = 64; // Because of SHA512
+
+fn random_ristretto_point() -> RistrettoPoint {
+    let mut rng = OsRng;
+    let mut random_bits = [0u8; 64];
+    rng.fill_bytes(&mut random_bits);
+
+    // This is because RistrettoPoint is on an obsolete sha2 version
+    let mut bits = [0u8; 64];
+    let mut hasher = sha2::Sha512::new();
+    hasher.update(&random_bits[..]);
+    bits.copy_from_slice(&hasher.finalize());
+
+    RistrettoPoint::from_uniform_bytes(&bits)
+}
+
+#[test]
+fn client_registration_roundtrip() {
+    let pw = b"hunter2";
+    let mut rng = OsRng;
+    let sc = <RistrettoPoint as Group>::random_scalar(&mut rng);
+
+    // serialization order: scalar, password
+    let bytes: Vec<u8> = [&sc.as_bytes()[..], &pw[..]].concat();
+    let reg = ClientRegistration::<Default>::deserialize(&bytes[..]).unwrap();
+    let reg_bytes = reg.serialize();
+    assert_eq!(reg_bytes, bytes);
+}
+
+#[test]
+fn server_registration_roundtrip() {
+    // If we don't have envelope and client_pk, the server registration just
+    // contains the prf key
+    let mut rng = OsRng;
+    let oprf_key = <RistrettoPoint as Group>::random_scalar(&mut rng);
+    let mut oprf_bytes: Vec<u8> = vec![];
+    oprf_bytes.extend_from_slice(oprf_key.as_bytes());
+    let reg = ServerRegistration::<Default>::deserialize(&oprf_bytes[..]).unwrap();
+    let reg_bytes = reg.serialize();
+    assert_eq!(reg_bytes, oprf_bytes);
+
+    let mut ciphertext = [0u8; 32];
+    rng.fill_bytes(&mut ciphertext);
+
+    // Construct a mock envelope
+    let mut mock_envelope_bytes = Vec::new();
+    mock_envelope_bytes.extend_from_slice(&[1; 1]); // mode = 1
+    mock_envelope_bytes.extend_from_slice(&vec![0; NonceLen::to_usize()]); // empty nonce
+    mock_envelope_bytes.extend_from_slice(&ciphertext); // ciphertext which is an encrypted private key
+    mock_envelope_bytes.extend_from_slice(&[0; MAC_SIZE]); // length-MAC_SIZE hmac
+
+    let mock_client_kp = Default::generate_random_keypair(&mut rng);
+    // serialization order: oprf_key, public key, envelope
+    let mut bytes = Vec::<u8>::new();
+    bytes.extend_from_slice(oprf_key.as_bytes());
+    bytes.extend_from_slice(&mock_client_kp.public().to_arr());
+    bytes.extend_from_slice(&mock_envelope_bytes);
+    let reg = ServerRegistration::<Default>::deserialize(&bytes[..]).unwrap();
+    let reg_bytes = reg.serialize();
+    assert_eq!(reg_bytes, bytes);
+}
+
+#[test]
+fn registration_request_roundtrip() {
+    let pt = random_ristretto_point();
+    let pt_bytes = pt.to_arr().to_vec();
+
+    let mut input = Vec::new();
+    input.extend_from_slice(pt_bytes.as_slice());
+
+    let r1 = RegistrationRequest::<Default>::deserialize(input.as_slice()).unwrap();
+    let r1_bytes = r1.serialize();
+    assert_eq!(input, r1_bytes);
+}
+
+#[test]
+fn registration_response_roundtrip() {
+    let pt = random_ristretto_point();
+    let beta_bytes = pt.to_arr();
+    let mut rng = OsRng;
+    let skp = Default::generate_random_keypair(&mut rng);
+    let pubkey_bytes = skp.public().to_arr();
+
+    let mut input = Vec::new();
+    input.extend_from_slice(beta_bytes.as_slice());
+    input.extend_from_slice(&pubkey_bytes.as_slice());
+
+    let r2 = RegistrationResponse::<Default>::deserialize(input.as_slice()).unwrap();
+    let r2_bytes = r2.serialize();
+    assert_eq!(input, r2_bytes);
+}
+
+#[test]
+fn registration_upload_roundtrip() {
+    let mut rng = OsRng;
+    let skp = Default::generate_random_keypair(&mut rng);
+    let pubkey_bytes = skp.public().to_arr();
+
+    let mut key = [0u8; 32];
+    rng.fill_bytes(&mut key);
+
+    let mut msg = [0u8; 32];
+    rng.fill_bytes(&mut msg);
+
+    let (envelope, _) = Envelope::<sha2::Sha512>::seal_raw(
+        &mut rng,
+        &key,
+        &msg,
+        &pubkey_bytes,
+        InnerEnvelopeMode::Base,
+    )
+    .unwrap();
+    let envelope_bytes = envelope.serialize();
+
+    let mut input = Vec::new();
+    input.extend_from_slice(&pubkey_bytes[..]);
+    input.extend_from_slice(&envelope_bytes);
+
+    let r3 = RegistrationUpload::<Default>::deserialize(&input[..]).unwrap();
+    let r3_bytes = r3.serialize();
+    assert_eq!(input, r3_bytes);
+}
+
+#[test]
+fn credential_request_roundtrip() {
+    let mut rng = OsRng;
+    let alpha = random_ristretto_point();
+    let alpha_bytes = alpha.to_arr().to_vec();
+
+    let client_e_kp = Default::generate_random_keypair(&mut rng);
+    let mut client_nonce = vec![0u8; NonceLen::to_usize()];
+    rng.fill_bytes(&mut client_nonce);
+
+    let mut info = [0u8; MAX_INFO_LENGTH];
+    rng.fill_bytes(&mut info);
+
+    let ke1m: Vec<u8> = [
+        &client_nonce[..],
+        &serialize(&info.to_vec(), 2),
+        &client_e_kp.public(),
+    ]
+    .concat();
+
+    let mut input = Vec::new();
+    input.extend_from_slice(&alpha_bytes);
+    input.extend_from_slice(&ke1m[..]);
+
+    let l1 = CredentialRequest::<Default>::deserialize(input.as_slice()).unwrap();
+    let l1_bytes = l1.serialize();
+    assert_eq!(input, l1_bytes);
+}
+
+#[test]
+fn credential_response_roundtrip() {
+    let pt = random_ristretto_point();
+    let pt_bytes = pt.to_arr().to_vec();
+
+    let mut rng = OsRng;
+    let skp = Default::generate_random_keypair(&mut rng);
+    let pubkey_bytes = skp.public().to_arr();
+
+    let mut key = [0u8; 32];
+    rng.fill_bytes(&mut key);
+
+    let mut msg = [0u8; 32];
+    rng.fill_bytes(&mut msg);
+
+    let (envelope, _) = Envelope::<sha2::Sha512>::seal_raw(
+        &mut rng,
+        &key,
+        &msg,
+        &pubkey_bytes,
+        InnerEnvelopeMode::Base,
+    )
+    .unwrap();
+
+    let server_e_kp = Default::generate_random_keypair(&mut rng);
+    let mut mac = [0u8; MAC_SIZE];
+    rng.fill_bytes(&mut mac);
+    let mut server_nonce = vec![0u8; NonceLen::to_usize()];
+    rng.fill_bytes(&mut server_nonce);
+
+    let mut e_info = [0u8; MAX_INFO_LENGTH];
+    rng.fill_bytes(&mut e_info);
+
+    let ke2m: Vec<u8> = [
+        &server_nonce[..],
+        &server_e_kp.public(),
+        &serialize(&e_info.to_vec(), 2),
+        &mac[..],
+    ]
+    .concat();
+
+    let mut input = Vec::new();
+    input.extend_from_slice(pt_bytes.as_slice());
+    input.extend_from_slice(&pubkey_bytes.as_slice());
+    input.extend_from_slice(&envelope.serialize());
+    input.extend_from_slice(&ke2m[..]);
+
+    let l2 = CredentialResponse::<Default>::deserialize(&input).unwrap();
+    let l2_bytes = l2.serialize();
+    assert_eq!(input, l2_bytes);
+}
+
+#[test]
+fn login_third_message_roundtrip() {
+    let mut rng = OsRng;
+    let mut mac = [0u8; MAC_SIZE];
+    rng.fill_bytes(&mut mac);
+
+    let input: Vec<u8> = [&mac[..]].concat();
+
+    let l3 = CredentialFinalization::<Default>::deserialize(&input).unwrap();
+    let l3_bytes = l3.serialize();
+    assert_eq!(input, l3_bytes);
+}
+
+#[test]
+fn client_login_roundtrip() {
+    let pw = b"hunter2";
+    let mut rng = OsRng;
+    let sc = <RistrettoPoint as Group>::random_scalar(&mut rng);
+
+    let client_e_kp = Default::generate_random_keypair(&mut rng);
+    let mut client_nonce = vec![0u8; NonceLen::to_usize()];
+    rng.fill_bytes(&mut client_nonce);
+
+    let serialized_credential_request = b"serialized credential_request".to_vec();
+    let l1_data = [client_e_kp.private().to_arr().to_vec(), client_nonce].concat();
+
+    // serialization order: scalar, credential_request, ke1_state, password
+    let bytes: Vec<u8> = [
+        &sc.as_bytes()[..],
+        &serialize(&serialized_credential_request, 2),
+        &serialize(&l1_data, 2),
+        &pw[..],
+    ]
+    .concat();
+    let reg = ClientLogin::<Default>::deserialize(&bytes[..]).unwrap();
+    let reg_bytes = reg.serialize();
+    assert_eq!(reg_bytes, bytes);
+}
+
+#[test]
+fn ke1_message_roundtrip() {
+    let mut rng = OsRng;
+
+    let client_e_kp = Default::generate_random_keypair(&mut rng);
+    let mut client_nonce = vec![0u8; NonceLen::to_usize()];
+    rng.fill_bytes(&mut client_nonce);
+
+    let mut info = [0u8; MAX_INFO_LENGTH];
+    rng.fill_bytes(&mut info);
+
+    let ke1m: Vec<u8> = [
+        &client_nonce[..],
+        &serialize(&info.to_vec(), 2),
+        &client_e_kp.public(),
+    ]
+    .concat();
+    let reg =
+        <TripleDH as KeyExchange<sha2::Sha512, RistrettoPoint>>::KE1Message::try_from(&ke1m[..])
+            .unwrap();
+    let reg_bytes = reg.to_bytes();
+    assert_eq!(reg_bytes, ke1m);
+}
+
+#[test]
+fn ke2_message_roundtrip() {
+    let mut rng = OsRng;
+
+    let server_e_kp = Default::generate_random_keypair(&mut rng);
+    let mut mac = [0u8; MAC_SIZE];
+    rng.fill_bytes(&mut mac);
+    let mut server_nonce = vec![0u8; NonceLen::to_usize()];
+    rng.fill_bytes(&mut server_nonce);
+    let mut e_info = [0u8; MAX_INFO_LENGTH];
+    rng.fill_bytes(&mut e_info);
+
+    let ke2m: Vec<u8> = [
+        &server_nonce[..],
+        &server_e_kp.public(),
+        &serialize(&e_info.to_vec(), 2),
+        &mac[..],
+    ]
+    .concat();
+
+    let reg =
+        <TripleDH as KeyExchange<sha2::Sha512, RistrettoPoint>>::KE2Message::try_from(&ke2m[..])
+            .unwrap();
+    let reg_bytes = reg.to_bytes();
+    assert_eq!(reg_bytes, ke2m);
+}
+
+#[test]
+fn ke3_message_roundtrip() {
+    let mut rng = OsRng;
+    let mut mac = [0u8; MAC_SIZE];
+    rng.fill_bytes(&mut mac);
+
+    let ke3m: Vec<u8> = [&mac[..]].concat();
+
+    let reg =
+        <TripleDH as KeyExchange<sha2::Sha512, RistrettoPoint>>::KE3Message::try_from(&ke3m[..])
+            .unwrap();
+    let reg_bytes = reg.to_bytes();
+    assert_eq!(reg_bytes, ke3m);
+}
+
+proptest! {
+
+#[test]
+fn test_i2osp_os2ip(bytes in vec(any::<u8>(), 0..std::mem::size_of::<usize>())) {
+    assert_eq!(i2osp(os2ip(&bytes)?, bytes.len()), bytes);
+}
+
+#[test]
+fn test_nocrash_registration_request(bytes in vec(any::<u8>(), 0..200)) {
+    RegistrationRequest::<Default>::deserialize(&bytes[..]).map_or(true, |_| true);
+}
+
+#[test]
+fn test_nocrash_registration_response(bytes in vec(any::<u8>(), 0..200)) {
+    RegistrationResponse::<Default>::deserialize(&bytes[..]).map_or(true, |_| true);
+}
+
+#[test]
+fn test_nocrash_registration_upload(bytes in vec(any::<u8>(), 0..200)) {
+    RegistrationUpload::<Default>::deserialize(&bytes[..]).map_or(true, |_| true);
+}
+
+#[test]
+fn test_nocrash_credential_request(bytes in vec(any::<u8>(), 0..500)) {
+    CredentialRequest::<Default>::deserialize(&bytes[..]).map_or(true, |_| true);
+}
+
+#[test]
+fn test_nocrash_credential_response(bytes in vec(any::<u8>(), 0..500)) {
+    CredentialResponse::<Default>::deserialize(&bytes[..]).map_or(true, |_| true);
+}
+
+#[test]
+fn test_nocrash_credential_finalization(bytes in vec(any::<u8>(), 0..500)) {
+    CredentialFinalization::<Default>::deserialize(&bytes[..]).map_or(true, |_| true);
+}
+
+#[test]
+fn test_nocrash_client_registration(bytes in vec(any::<u8>(), 0..700)) {
+    ClientRegistration::<Default>::deserialize(&bytes[..]).map_or(true, |_| true);
+}
+
+#[test]
+fn test_nocrash_server_registration(bytes in vec(any::<u8>(), 0..700)) {
+    ServerRegistration::<Default>::deserialize(&bytes[..]).map_or(true, |_| true);
+}
+
+#[test]
+fn test_nocrash_client_login(bytes in vec(any::<u8>(), 0..700)) {
+    ClientLogin::<Default>::deserialize(&bytes[..]).map_or(true, |_| true);
+}
+
+#[test]
+fn test_nocrash_server_login(bytes in vec(any::<u8>(), 0..700)) {
+    ServerLogin::<Default>::deserialize(&bytes[..]).map_or(true, |_| true);
+}
+
+}

src/slow_hash.rs

@@ -5,9 +5,10 @@
 
 //! Trait specifying a slow hashing function
 
-use crate::errors::InternalPakeError;
-use crate::hash::Hash;
+use crate::{errors::InternalPakeError, hash::Hash};
 use digest::Digest;
+#[cfg(feature = "slow-hash")]
+use generic_array::typenum::Unsigned;
 use generic_array::GenericArray;
 
 /// Used for the slow hashing function in OPAQUE
@@ -29,15 +30,24 @@ impl<D: Hash> SlowHash<D> for NoOpHash {
     }
 }
 
+#[cfg(feature = "slow-hash")]
+const DEFAULT_SCRYPT_LOG_N: u8 = 15u8;
+#[cfg(feature = "slow-hash")]
+const DEFAULT_SCRYPT_R: u32 = 8u32;
+#[cfg(feature = "slow-hash")]
+const DEFAULT_SCRYPT_P: u32 = 1u32;
+
 #[cfg(feature = "slow-hash")]
 impl<D: Hash> SlowHash<D> for scrypt::ScryptParams {
     fn hash(
         input: GenericArray<u8, <D as Digest>::OutputSize>,
     ) -> Result<Vec<u8>, InternalPakeError> {
-        let params = scrypt::ScryptParams::new(15, 8, 1).unwrap();
-        let mut output = [0u8; <D as Digest>::OutputSize::to_usize()];
+        let params =
+            scrypt::ScryptParams::new(DEFAULT_SCRYPT_LOG_N, DEFAULT_SCRYPT_R, DEFAULT_SCRYPT_P)
+                .map_err(|_| InternalPakeError::SlowHashError)?;
+        let mut output = vec![0u8; <D as Digest>::OutputSize::to_usize()];
         scrypt::scrypt(&input, &[], &params, &mut output)
             .map_err(|_| InternalPakeError::SlowHashError)?;
-        Ok(output.to_vec())
+        Ok(output)
     }
 }

src/tests/full_test.rs

@@ -0,0 +1,708 @@
+// Copyright (c) Facebook, Inc. and its affiliates.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+use crate::{
+    ciphersuite::CipherSuite,
+    errors::*,
+    group::Group,
+    key_exchange::tripledh::{NonceLen, TripleDH},
+    keypair::{Key, SizedBytesExt},
+    opaque::*,
+    slow_hash::NoOpHash,
+    tests::mock_rng::CycleRng,
+    *,
+};
+use curve25519_dalek::ristretto::RistrettoPoint;
+use generic_array::typenum::Unsigned;
+use generic_bytes::SizedBytes;
+use rand::{rngs::OsRng, RngCore};
+use serde_json::Value;
+
+// Tests
+// =====
+
+struct RistrettoSha5123dhNoSlowHash;
+impl CipherSuite for RistrettoSha5123dhNoSlowHash {
+    type Group = RistrettoPoint;
+    type KeyExchange = TripleDH;
+    type Hash = sha2::Sha512;
+    type SlowHash = NoOpHash;
+}
+
+pub struct TestVectorParameters {
+    pub client_s_pk: Vec<u8>,
+    pub client_s_sk: Vec<u8>,
+    pub client_e_pk: Vec<u8>,
+    pub client_e_sk: Vec<u8>,
+    pub server_s_pk: Vec<u8>,
+    pub server_s_sk: Vec<u8>,
+    pub server_e_pk: Vec<u8>,
+    pub server_e_sk: Vec<u8>,
+    pub id_u: Vec<u8>,
+    pub id_s: Vec<u8>,
+    pub password: Vec<u8>,
+    pub blinding_factor: Vec<u8>,
+    pub oprf_key: Vec<u8>,
+    pub envelope_nonce: Vec<u8>,
+    pub client_nonce: Vec<u8>,
+    pub server_nonce: Vec<u8>,
+    pub info1: Vec<u8>,
+    pub einfo2: Vec<u8>,
+    pub registration_request: Vec<u8>,
+    pub registration_response: Vec<u8>,
+    pub registration_upload: Vec<u8>,
+    pub credential_request: Vec<u8>,
+    pub credential_response: Vec<u8>,
+    pub credential_finalization: Vec<u8>,
+    client_registration_state: Vec<u8>,
+    server_registration_state: Vec<u8>,
+    client_login_state: Vec<u8>,
+    server_login_state: Vec<u8>,
+    pub password_file: Vec<u8>,
+    pub export_key: Vec<u8>,
+    pub session_key: Vec<u8>,
+}
+
+static TEST_VECTOR: &str = r#"
+{
+    "client_s_pk": "6e0a6082dd29936c44b47ecb8a5fe72e4b321a0ac314b0080ca4c48afdabd215",
+    "client_s_sk": "3000848b34d9073885d427e766b7093cc13bdce992ef31cd00ba2c77ff074504",
+    "client_e_pk": "5260ad6eb47ac1db44babcce9327327d50e1a0133c0425acca3efcf41b119718",
+    "client_e_sk": "1526e0bed9af28830da956589d65768ed2a20d9689e82c90b89e4e33904e4009",
+    "server_s_pk": "c21a38653eb19437669bfa066a446b6eea7c1f253ac7adf4798d6c68e171b273",
+    "server_s_sk": "2a38b385e9fb7e0a89aa0f005c729b0c4e22eeedea8c105cf136d9c5c334880f",
+    "server_e_pk": "125f4a2dd9353c8c37a08527a323908835d3fbc374260d32e829d5c3fa81f325",
+    "server_e_sk": "7ef6ada36f3983c0f24705a29d3a453e3e17c28d347f226b24c0aa5ab12a700d",
+    "id_u": "696455",
+    "id_s": "696453",
+    "password": "70617373776f7264",
+    "blinding_factor": "a32862d66eb57246321fb6b229e83786745c3afdf8957ebe38b01c17571ba105",
+    "oprf_key": "0851f5ec43e0b702bfcb9d8ec208085b51c0fc5200234901407c176327aa0b02",
+    "envelope_nonce": "78b006042d011bdca5d0058a978d2103a6d546de311a2e8cd025fbc67303a468",
+    "client_nonce": "43497a6f86ba31a6a7f399271fb3b4b4f82c4af086bc431ebaeab7d768ff8a64",
+    "server_nonce": "680cd27da18bc56d4317e7db61de1726a70ebe4e49aee38a3bdb6787cf85466e",
+    "info1": "696e666f31",
+    "einfo2": "65696e666f32",
+    "registration_request": "14ba86e53018ce5507d2bfb2d98ad3f60e302d826bff3410a5ec669c8e1ef17d",
+    "registration_response": "aee5c937a85acfbdbd71faf1c5519bfe9e44b0b7489dcc663df9f1ca5b520b6ac21a38653eb19437669bfa066a446b6eea7c1f253ac7adf4798d6c68e171b273",
+    "registration_upload": "6e0a6082dd29936c44b47ecb8a5fe72e4b321a0ac314b0080ca4c48afdabd2150278b006042d011bdca5d0058a978d2103a6d546de311a2e8cd025fbc67303a4687618b32fe2ec2a5c2b6efecec1e6e535106de80af68733673daf0b644965966fa3f279e532d7ecef363f8d55ff6df4c473cfb1049a73f632972bfcc6744185d13a671dd6678d49fb1629a6fbfbe266937378fd9e772c2dd72692d1a35c020010",
+    "credential_request": "14ba86e53018ce5507d2bfb2d98ad3f60e302d826bff3410a5ec669c8e1ef17d43497a6f86ba31a6a7f399271fb3b4b4f82c4af086bc431ebaeab7d768ff8a640005696e666f315260ad6eb47ac1db44babcce9327327d50e1a0133c0425acca3efcf41b119718",
+    "credential_response": "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",
+    "credential_finalization": "330aa8ac01bbc9d9642fe1c286187379efe12da14aceab86b22449d21f242d89adabc0295751b4e007beabc413ae9cbf9979e324749953705fd85b87c9c1b1a2",
+    "client_registration_state": "a32862d66eb57246321fb6b229e83786745c3afdf8957ebe38b01c17571ba10570617373776f7264",
+    "client_login_state": "a32862d66eb57246321fb6b229e83786745c3afdf8957ebe38b01c17571ba105006714ba86e53018ce5507d2bfb2d98ad3f60e302d826bff3410a5ec669c8e1ef17d43497a6f86ba31a6a7f399271fb3b4b4f82c4af086bc431ebaeab7d768ff8a640005696e666f315260ad6eb47ac1db44babcce9327327d50e1a0133c0425acca3efcf41b11971800401526e0bed9af28830da956589d65768ed2a20d9689e82c90b89e4e33904e400943497a6f86ba31a6a7f399271fb3b4b4f82c4af086bc431ebaeab7d768ff8a6470617373776f7264",
+    "server_registration_state": "0851f5ec43e0b702bfcb9d8ec208085b51c0fc5200234901407c176327aa0b02",
+    "server_login_state": "89cd93dce8f59cf7b187736c50cbc3ca2e0bbbad0a0be1ddee180a2d95db60695b384be2dd673434ef94bcdbb1b457f63f41cd79ed2422c021c34ca1433b70576920ebb950ad1c40c8c015ec6832e12427e755ba21d005f0b6d5d66d2368ab5ec6f32151fced5a3aa25472c425912242de3638ef57f28b0dd02a956064e5bb9b8fcd73add52d233a454d6b20125e9506a95aae8772ebbfac4d70efe1fb10078fd40f93d84aa7db53853ca74436c917c427cd5c2e408860937e6f7ab80816ca47",
+    "password_file": "0851f5ec43e0b702bfcb9d8ec208085b51c0fc5200234901407c176327aa0b026e0a6082dd29936c44b47ecb8a5fe72e4b321a0ac314b0080ca4c48afdabd2150278b006042d011bdca5d0058a978d2103a6d546de311a2e8cd025fbc67303a4687618b32fe2ec2a5c2b6efecec1e6e535106de80af68733673daf0b644965966fa3f279e532d7ecef363f8d55ff6df4c473cfb1049a73f632972bfcc6744185d13a671dd6678d49fb1629a6fbfbe266937378fd9e772c2dd72692d1a35c020010",
+    "export_key": "8197f91f0d4de1ab126d8dfd06abd0d5df420ce40a135ef376e4ffe515930f413632390e7dc3dcfd19afff62b9113e10eb6c359fc327df6e9ad4d0f06c242322",
+    "session_key": "8fcd73add52d233a454d6b20125e9506a95aae8772ebbfac4d70efe1fb10078fd40f93d84aa7db53853ca74436c917c427cd5c2e408860937e6f7ab80816ca47"
+}
+"#;
+
+fn decode(values: &Value, key: &str) -> Option<Vec<u8>> {
+    values[key]
+        .as_str()
+        .and_then(|s| hex::decode(&s.to_string()).ok())
+}
+
+fn populate_test_vectors(values: &Value) -> TestVectorParameters {
+    TestVectorParameters {
+        client_s_pk: decode(&values, "client_s_pk").unwrap(),
+        client_s_sk: decode(&values, "client_s_sk").unwrap(),
+        client_e_pk: decode(&values, "client_e_pk").unwrap(),
+        client_e_sk: decode(&values, "client_e_sk").unwrap(),
+        server_s_pk: decode(&values, "server_s_pk").unwrap(),
+        server_s_sk: decode(&values, "server_s_sk").unwrap(),
+        server_e_pk: decode(&values, "server_e_pk").unwrap(),
+        server_e_sk: decode(&values, "server_e_sk").unwrap(),
+        id_u: decode(&values, "id_u").unwrap(),
+        id_s: decode(&values, "id_s").unwrap(),
+        password: decode(&values, "password").unwrap(),
+        blinding_factor: decode(&values, "blinding_factor").unwrap(),
+        oprf_key: decode(&values, "oprf_key").unwrap(),
+        envelope_nonce: decode(&values, "envelope_nonce").unwrap(),
+        client_nonce: decode(&values, "client_nonce").unwrap(),
+        server_nonce: decode(&values, "server_nonce").unwrap(),
+        info1: decode(&values, "info1").unwrap(),
+        einfo2: decode(&values, "einfo2").unwrap(),
+        registration_request: decode(&values, "registration_request").unwrap(),
+        registration_response: decode(&values, "registration_response").unwrap(),
+        registration_upload: decode(&values, "registration_upload").unwrap(),
+        credential_request: decode(&values, "credential_request").unwrap(),
+        credential_response: decode(&values, "credential_response").unwrap(),
+        credential_finalization: decode(&values, "credential_finalization").unwrap(),
+        client_registration_state: decode(&values, "client_registration_state").unwrap(),
+        client_login_state: decode(&values, "client_login_state").unwrap(),
+        server_registration_state: decode(&values, "server_registration_state").unwrap(),
+        server_login_state: decode(&values, "server_login_state").unwrap(),
+        password_file: decode(&values, "password_file").unwrap(),
+        export_key: decode(&values, "export_key").unwrap(),
+        session_key: decode(&values, "session_key").unwrap(),
+    }
+}
+
+fn stringify_test_vectors(p: &TestVectorParameters) -> String {
+    let mut s = String::new();
+    s.push_str("{\n");
+    s.push_str(format!("\"client_s_pk\": \"{}\",\n", hex::encode(&p.client_s_pk)).as_str());
+    s.push_str(format!("\"client_s_sk\": \"{}\",\n", hex::encode(&p.client_s_sk)).as_str());
+    s.push_str(format!("\"client_e_pk\": \"{}\",\n", hex::encode(&p.client_e_pk)).as_str());
+    s.push_str(format!("\"client_e_sk\": \"{}\",\n", hex::encode(&p.client_e_sk)).as_str());
+    s.push_str(format!("\"server_s_pk\": \"{}\",\n", hex::encode(&p.server_s_pk)).as_str());
+    s.push_str(format!("\"server_s_sk\": \"{}\",\n", hex::encode(&p.server_s_sk)).as_str());
+    s.push_str(format!("\"server_e_pk\": \"{}\",\n", hex::encode(&p.server_e_pk)).as_str());
+    s.push_str(format!("\"server_e_sk\": \"{}\",\n", hex::encode(&p.server_e_sk)).as_str());
+    s.push_str(format!("\"id_u\": \"{}\",\n", hex::encode(&p.id_u)).as_str());
+    s.push_str(format!("\"id_s\": \"{}\",\n", hex::encode(&p.id_s)).as_str());
+    s.push_str(format!("\"password\": \"{}\",\n", hex::encode(&p.password)).as_str());
+    s.push_str(
+        format!(
+            "\"blinding_factor\": \"{}\",\n",
+            hex::encode(&p.blinding_factor)
+        )
+        .as_str(),
+    );
+    s.push_str(format!("\"oprf_key\": \"{}\",\n", hex::encode(&p.oprf_key)).as_str());
+    s.push_str(
+        format!(
+            "\"envelope_nonce\": \"{}\",\n",
+            hex::encode(&p.envelope_nonce)
+        )
+        .as_str(),
+    );
+    s.push_str(format!("\"client_nonce\": \"{}\",\n", hex::encode(&p.client_nonce)).as_str());
+    s.push_str(format!("\"server_nonce\": \"{}\",\n", hex::encode(&p.server_nonce)).as_str());
+    s.push_str(format!("\"info1\": \"{}\",\n", hex::encode(&p.info1)).as_str());
+    s.push_str(format!("\"einfo2\": \"{}\",\n", hex::encode(&p.einfo2)).as_str());
+    s.push_str(
+        format!(
+            "\"registration_request\": \"{}\",\n",
+            hex::encode(&p.registration_request)
+        )
+        .as_str(),
+    );
+    s.push_str(
+        format!(
+            "\"registration_response\": \"{}\",\n",
+            hex::encode(&p.registration_response)
+        )
+        .as_str(),
+    );
+    s.push_str(
+        format!(
+            "\"registration_upload\": \"{}\",\n",
+            hex::encode(&p.registration_upload)
+        )
+        .as_str(),
+    );
+    s.push_str(
+        format!(
+            "\"credential_request\": \"{}\",\n",
+            hex::encode(&p.credential_request)
+        )
+        .as_str(),
+    );
+    s.push_str(
+        format!(
+            "\"credential_response\": \"{}\",\n",
+            hex::encode(&p.credential_response)
+        )
+        .as_str(),
+    );
+    s.push_str(
+        format!(
+            "\"credential_finalization\": \"{}\",\n",
+            hex::encode(&p.credential_finalization)
+        )
+        .as_str(),
+    );
+    s.push_str(
+        format!(
+            "\"client_registration_state\": \"{}\",\n",
+            hex::encode(&p.client_registration_state)
+        )
+        .as_str(),
+    );
+    s.push_str(
+        format!(
+            "\"client_login_state\": \"{}\",\n",
+            hex::encode(&p.client_login_state)
+        )
+        .as_str(),
+    );
+    s.push_str(
+        format!(
+            "\"server_registration_state\": \"{}\",\n",
+            hex::encode(&p.server_registration_state)
+        )
+        .as_str(),
+    );
+    s.push_str(
+        format!(
+            "\"server_login_state\": \"{}\",\n",
+            hex::encode(&p.server_login_state)
+        )
+        .as_str(),
+    );
+    s.push_str(
+        format!(
+            "\"password_file\": \"{}\",\n",
+            hex::encode(&p.password_file)
+        )
+        .as_str(),
+    );
+    s.push_str(format!("\"export_key\": \"{}\",\n", hex::encode(&p.export_key)).as_str());
+    s.push_str(format!("\"session_key\": \"{}\"\n", hex::encode(&p.session_key)).as_str());
+    s.push_str("}\n");
+    s
+}
+
+fn generate_parameters<CS: CipherSuite>() -> TestVectorParameters {
+    let mut rng = OsRng;
+
+    // Inputs
+    let server_s_kp = CS::generate_random_keypair(&mut rng);
+    let server_e_kp = CS::generate_random_keypair(&mut rng);
+    let client_s_kp = CS::generate_random_keypair(&mut rng);
+    let client_e_kp = CS::generate_random_keypair(&mut rng);
+    let id_u = b"idU";
+    let id_s = b"idS";
+    let password = b"password";
+    let mut oprf_key_raw = [0u8; 32];
+    rng.fill_bytes(&mut oprf_key_raw);
+    let mut envelope_nonce = [0u8; 32];
+    rng.fill_bytes(&mut envelope_nonce);
+    let mut client_nonce = vec![0u8; NonceLen::to_usize()];
+    rng.fill_bytes(&mut client_nonce);
+    let mut server_nonce = vec![0u8; NonceLen::to_usize()];
+    rng.fill_bytes(&mut server_nonce);
+
+    let blinding_factor = CS::Group::random_scalar(&mut rng);
+    let blinding_factor_bytes = CS::Group::scalar_as_bytes(&blinding_factor).clone();
+
+    let info1 = b"info1";
+    let einfo2 = b"einfo2";
+
+    let mut blinding_factor_registration_rng = CycleRng::new(blinding_factor_bytes.to_vec());
+    let client_registration_start_result =
+        ClientRegistration::<CS>::start(&mut blinding_factor_registration_rng, password).unwrap();
+    let blinding_factor_bytes_returned =
+        CS::Group::scalar_as_bytes(&client_registration_start_result.state.token.blind).clone();
+    assert_eq!(
+        hex::encode(&blinding_factor_bytes),
+        hex::encode(&blinding_factor_bytes_returned)
+    );
+
+    let registration_request_bytes = client_registration_start_result
+        .message
+        .serialize()
+        .to_vec();
+    let client_registration_state = client_registration_start_result.state.serialize().to_vec();
+
+    let mut oprf_key_rng = CycleRng::new(oprf_key_raw.to_vec());
+    let server_registration_start_result = ServerRegistration::<CS>::start(
+        &mut oprf_key_rng,
+        client_registration_start_result.message,
+        server_s_kp.public(),
+    )
+    .unwrap();
+    let registration_response_bytes = server_registration_start_result
+        .message
+        .serialize()
+        .to_vec();
+    let oprf_key_bytes =
+        CS::Group::scalar_as_bytes(&server_registration_start_result.state.oprf_key).clone();
+    let server_registration_state = server_registration_start_result.state.serialize().to_vec();
+
+    let mut client_s_sk_and_nonce: Vec<u8> = Vec::new();
+    client_s_sk_and_nonce.extend_from_slice(&client_s_kp.private().to_arr());
+    client_s_sk_and_nonce.extend_from_slice(&envelope_nonce);
+
+    let mut finish_registration_rng = CycleRng::new(client_s_sk_and_nonce);
+    let client_registration_finish_result = client_registration_start_result
+        .state
+        .finish(
+            &mut finish_registration_rng,
+            server_registration_start_result.message,
+            ClientRegistrationFinishParameters::WithIdentifiers(id_u.to_vec(), id_s.to_vec()),
+        )
+        .unwrap();
+    let registration_upload_bytes = client_registration_finish_result
+        .message
+        .serialize()
+        .to_vec();
+
+    let password_file = server_registration_start_result
+        .state
+        .finish(client_registration_finish_result.message)
+        .unwrap();
+    let password_file_bytes = password_file.serialize();
+
+    let mut client_login_start: Vec<u8> = Vec::new();
+    client_login_start.extend_from_slice(&blinding_factor_bytes);
+    client_login_start.extend_from_slice(&client_e_kp.private().to_arr());
+    client_login_start.extend_from_slice(&client_nonce);
+
+    let mut client_login_start_rng = CycleRng::new(client_login_start);
+    let client_login_start_result = ClientLogin::<CS>::start(
+        &mut client_login_start_rng,
+        password,
+        ClientLoginStartParameters::WithInfo(info1.to_vec()),
+    )
+    .unwrap();
+    let credential_request_bytes = client_login_start_result.message.serialize().to_vec();
+    let client_login_state = client_login_start_result.state.serialize().to_vec();
+
+    let mut server_e_sk_and_nonce_rng = CycleRng::new(
+        [
+            server_e_kp.private().to_arr().to_vec(),
+            server_nonce.to_vec(),
+        ]
+        .concat(),
+    );
+    let server_login_start_result = ServerLogin::<CS>::start(
+        &mut server_e_sk_and_nonce_rng,
+        password_file,
+        server_s_kp.private(),
+        client_login_start_result.message,
+        ServerLoginStartParameters::WithInfoAndIdentifiers(
+            einfo2.to_vec(),
+            id_u.to_vec(),
+            id_s.to_vec(),
+        ),
+    )
+    .unwrap();
+    let credential_response_bytes = server_login_start_result.message.serialize().to_vec();
+    let server_login_state = server_login_start_result.state.serialize().to_vec();
+
+    let client_login_finish_result = client_login_start_result
+        .state
+        .finish(
+            server_login_start_result.message,
+            ClientLoginFinishParameters::WithIdentifiers(id_u.to_vec(), id_s.to_vec()),
+        )
+        .unwrap();
+    let credential_finalization_bytes = client_login_finish_result.message.serialize();
+
+    TestVectorParameters {
+        client_s_pk: client_s_kp.public().to_arr().to_vec(),
+        client_s_sk: client_s_kp.private().to_arr().to_vec(),
+        client_e_pk: client_e_kp.public().to_arr().to_vec(),
+        client_e_sk: client_e_kp.private().to_arr().to_vec(),
+        server_s_pk: server_s_kp.public().to_arr().to_vec(),
+        server_s_sk: server_s_kp.private().to_arr().to_vec(),
+        server_e_pk: server_e_kp.public().to_arr().to_vec(),
+        server_e_sk: server_e_kp.private().to_arr().to_vec(),
+        id_u: id_u.to_vec(),
+        id_s: id_s.to_vec(),
+        password: password.to_vec(),
+        blinding_factor: blinding_factor_bytes.to_vec(),
+        oprf_key: oprf_key_bytes.to_vec(),
+        envelope_nonce: envelope_nonce.to_vec(),
+        client_nonce: client_nonce.to_vec(),
+        server_nonce: server_nonce.to_vec(),
+        info1: info1.to_vec(),
+        einfo2: einfo2.to_vec(),
+        registration_request: registration_request_bytes,
+        registration_response: registration_response_bytes,
+        registration_upload: registration_upload_bytes,
+        credential_request: credential_request_bytes,
+        credential_response: credential_response_bytes,
+        credential_finalization: credential_finalization_bytes,
+        password_file: password_file_bytes,
+        client_registration_state,
+        server_registration_state,
+        client_login_state,
+        server_login_state,
+        session_key: client_login_finish_result.session_key,
+        export_key: client_registration_finish_result.export_key.to_vec(),
+    }
+}
+
+#[test]
+fn generate_test_vectors() {
+    let parameters = generate_parameters::<RistrettoSha5123dhNoSlowHash>();
+    println!("{}", stringify_test_vectors(&parameters));
+}
+
+#[test]
+fn test_registration_request() -> Result<(), ProtocolError> {
+    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
+    let mut rng = CycleRng::new(parameters.blinding_factor.to_vec());
+    let client_registration_start_result =
+        ClientRegistration::<RistrettoSha5123dhNoSlowHash>::start(&mut rng, &parameters.password)?;
+    assert_eq!(
+        hex::encode(&parameters.registration_request),
+        hex::encode(client_registration_start_result.message.serialize())
+    );
+    assert_eq!(
+        hex::encode(&parameters.client_registration_state),
+        hex::encode(client_registration_start_result.state.serialize())
+    );
+    Ok(())
+}
+
+#[test]
+fn test_registration_response() -> Result<(), ProtocolError> {
+    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
+    let mut oprf_key_rng = CycleRng::new(parameters.oprf_key);
+    let server_registration_start_result =
+        ServerRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut oprf_key_rng,
+            RegistrationRequest::deserialize(&parameters.registration_request[..])?,
+            &Key::from_bytes(&parameters.server_s_pk[..])?,
+        )?;
+    assert_eq!(
+        hex::encode(parameters.registration_response),
+        hex::encode(server_registration_start_result.message.serialize())
+    );
+    assert_eq!(
+        hex::encode(&parameters.server_registration_state),
+        hex::encode(server_registration_start_result.state.serialize())
+    );
+    Ok(())
+}
+
+#[test]
+fn test_registration_upload() -> Result<(), ProtocolError> {
+    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
+
+    let client_s_sk_and_nonce: Vec<u8> =
+        [parameters.client_s_sk, parameters.envelope_nonce].concat();
+    let mut finish_registration_rng = CycleRng::new(client_s_sk_and_nonce);
+    let result = ClientRegistration::<RistrettoSha5123dhNoSlowHash>::deserialize(
+        &parameters.client_registration_state[..],
+    )?
+    .finish(
+        &mut finish_registration_rng,
+        RegistrationResponse::deserialize(&parameters.registration_response[..])?,
+        ClientRegistrationFinishParameters::WithIdentifiers(parameters.id_u, parameters.id_s),
+    )?;
+
+    assert_eq!(
+        hex::encode(parameters.registration_upload),
+        hex::encode(result.message.serialize())
+    );
+    assert_eq!(
+        hex::encode(parameters.export_key),
+        hex::encode(result.export_key.to_vec())
+    );
+
+    Ok(())
+}
+
+#[test]
+fn test_password_file() -> Result<(), ProtocolError> {
+    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
+
+    let server_registration = ServerRegistration::<RistrettoSha5123dhNoSlowHash>::deserialize(
+        &parameters.server_registration_state[..],
+    )?;
+    let password_file = server_registration.finish(RegistrationUpload::deserialize(
+        &parameters.registration_upload[..],
+    )?)?;
+
+    assert_eq!(
+        hex::encode(parameters.password_file),
+        hex::encode(password_file.serialize())
+    );
+    Ok(())
+}
+
+#[test]
+fn test_credential_request() -> Result<(), ProtocolError> {
+    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
+
+    let client_login_start_rng = [
+        parameters.blinding_factor,
+        parameters.client_e_sk,
+        parameters.client_nonce,
+    ]
+    .concat();
+    let mut client_login_start_rng = CycleRng::new(client_login_start_rng);
+    let client_login_start_result = ClientLogin::<RistrettoSha5123dhNoSlowHash>::start(
+        &mut client_login_start_rng,
+        &parameters.password,
+        ClientLoginStartParameters::WithInfo(parameters.info1),
+    )?;
+    assert_eq!(
+        hex::encode(&parameters.credential_request),
+        hex::encode(client_login_start_result.message.serialize())
+    );
+    assert_eq!(
+        hex::encode(&parameters.client_login_state),
+        hex::encode(client_login_start_result.state.serialize())
+    );
+    Ok(())
+}
+
+#[test]
+fn test_credential_response() -> Result<(), ProtocolError> {
+    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
+
+    let mut server_e_sk_and_nonce_rng =
+        CycleRng::new([parameters.server_e_sk, parameters.server_nonce].concat());
+    let server_login_start_result = ServerLogin::<RistrettoSha5123dhNoSlowHash>::start(
+        &mut server_e_sk_and_nonce_rng,
+        ServerRegistration::deserialize(&parameters.password_file[..])?,
+        &Key::from_bytes(&parameters.server_s_sk[..])?,
+        CredentialRequest::<RistrettoSha5123dhNoSlowHash>::deserialize(
+            &parameters.credential_request[..],
+        )?,
+        ServerLoginStartParameters::WithInfoAndIdentifiers(
+            parameters.einfo2.to_vec(),
+            parameters.id_u,
+            parameters.id_s,
+        ),
+    )?;
+    assert_eq!(
+        hex::encode(&parameters.info1),
+        hex::encode(server_login_start_result.plain_info),
+    );
+    assert_eq!(
+        hex::encode(&parameters.credential_response),
+        hex::encode(server_login_start_result.message.serialize())
+    );
+    assert_eq!(
+        hex::encode(&parameters.server_login_state),
+        hex::encode(server_login_start_result.state.serialize())
+    );
+    Ok(())
+}
+
+#[test]
+fn test_credential_finalization() -> Result<(), ProtocolError> {
+    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
+
+    let client_login_finish_result = ClientLogin::<RistrettoSha5123dhNoSlowHash>::deserialize(
+        &parameters.client_login_state[..],
+    )?
+    .finish(
+        CredentialResponse::<RistrettoSha5123dhNoSlowHash>::deserialize(
+            &parameters.credential_response[..],
+        )?,
+        ClientLoginFinishParameters::WithIdentifiers(parameters.id_u, parameters.id_s),
+    )?;
+
+    assert_eq!(
+        hex::encode(&parameters.einfo2),
+        hex::encode(&client_login_finish_result.confidential_info)
+    );
+    assert_eq!(
+        hex::encode(&parameters.server_s_pk),
+        hex::encode(&client_login_finish_result.server_s_pk.to_arr().to_vec())
+    );
+    assert_eq!(
+        hex::encode(&parameters.session_key),
+        hex::encode(&client_login_finish_result.session_key)
+    );
+    assert_eq!(
+        hex::encode(&parameters.credential_finalization),
+        hex::encode(client_login_finish_result.message.serialize())
+    );
+    assert_eq!(
+        hex::encode(&parameters.export_key),
+        hex::encode(client_login_finish_result.export_key)
+    );
+
+    Ok(())
+}
+
+#[test]
+fn test_server_login_finish() -> Result<(), ProtocolError> {
+    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
+
+    let server_login_result = ServerLogin::<RistrettoSha5123dhNoSlowHash>::deserialize(
+        &parameters.server_login_state[..],
+    )?
+    .finish(CredentialFinalization::deserialize(
+        &parameters.credential_finalization[..],
+    )?)?;
+
+    assert_eq!(
+        hex::encode(parameters.session_key),
+        hex::encode(server_login_result.session_key)
+    );
+
+    Ok(())
+}
+
+fn test_complete_flow(
+    registration_password: &[u8],
+    login_password: &[u8],
+) -> Result<(), ProtocolError> {
+    let mut client_rng = OsRng;
+    let mut server_rng = OsRng;
+    let server_kp = RistrettoSha5123dhNoSlowHash::generate_random_keypair(&mut server_rng);
+    let client_registration_start_result =
+        ClientRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut client_rng,
+            registration_password,
+        )?;
+    let server_registration_start_result =
+        ServerRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut server_rng,
+            client_registration_start_result.message,
+            server_kp.public(),
+        )?;
+    let client_registration_finish_result = client_registration_start_result.state.finish(
+        &mut client_rng,
+        server_registration_start_result.message,
+        ClientRegistrationFinishParameters::default(),
+    )?;
+    let p_file = server_registration_start_result
+        .state
+        .finish(client_registration_finish_result.message)?;
+    let client_login_start_result = ClientLogin::<RistrettoSha5123dhNoSlowHash>::start(
+        &mut client_rng,
+        login_password,
+        ClientLoginStartParameters::default(),
+    )?;
+    let server_login_start_result = ServerLogin::<RistrettoSha5123dhNoSlowHash>::start(
+        &mut server_rng,
+        p_file,
+        &server_kp.private(),
+        client_login_start_result.message,
+        ServerLoginStartParameters::default(),
+    )?;
+
+    let client_login_result = client_login_start_result.state.finish(
+        server_login_start_result.message,
+        ClientLoginFinishParameters::default(),
+    );
+
+    if hex::encode(registration_password) == hex::encode(login_password) {
+        let client_login_finish_result = client_login_result?;
+        let server_login_finish_result = server_login_start_result
+            .state
+            .finish(client_login_finish_result.message)?;
+
+        assert_eq!(
+            hex::encode(server_login_finish_result.session_key),
+            hex::encode(client_login_finish_result.session_key)
+        );
+        assert_eq!(
+            hex::encode(client_registration_finish_result.export_key),
+            hex::encode(client_login_finish_result.export_key)
+        );
+    } else {
+        assert!(match client_login_result {
+            Err(ProtocolError::VerificationError(PakeError::InvalidLoginError)) => true,
+            _ => false,
+        });
+    }
+
+    Ok(())
+}
+
+#[test]
+fn test_complete_flow_success() -> Result<(), ProtocolError> {
+    test_complete_flow(b"good password", b"good password")
+}
+
+#[test]
+fn test_complete_flow_fail() -> Result<(), ProtocolError> {
+    test_complete_flow(b"good password", b"bad password")
+}

src/tests/mock_rng.rs

@@ -3,7 +3,7 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the root directory of this source tree.
 
-use rand_core::{CryptoRng, Error, RngCore};
+use rand::{CryptoRng, Error, RngCore};
 use std::cmp::min;
 
 /// A simple implementation of `RngCore` for testing purposes.

src/tests/mod.rs

@@ -3,6 +3,7 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the root directory of this source tree.
 
+mod full_test;
 pub mod mock_rng;
-mod opaque_ke_test;
-mod serialization;
+mod opaque_test_vectors;
+mod voprf_test_vectors;

src/tests/opaque_ke_test.rs

@@ -1,579 +0,0 @@
-// Copyright (c) Facebook, Inc. and its affiliates.
-//
-// This source code is licensed under the MIT license found in the
-// LICENSE file in the root directory of this source tree.
-
-use crate::{
-    ciphersuite::CipherSuite,
-    errors::*,
-    group::Group,
-    key_exchange::tripledh::{TripleDH, NONCE_LEN},
-    keypair::{Key, KeyPair, X25519KeyPair},
-    opaque::*,
-    slow_hash::NoOpHash,
-    tests::mock_rng::CycleRng,
-};
-use curve25519_dalek::edwards::EdwardsPoint;
-use rand_core::{OsRng, RngCore};
-use serde_json::Value;
-use std::convert::TryFrom;
-
-// Tests
-// =====
-
-struct X255193dhNoSlowHash;
-impl CipherSuite for X255193dhNoSlowHash {
-    type Group = EdwardsPoint;
-    type KeyFormat = X25519KeyPair;
-    type KeyExchange = TripleDH;
-    type Hash = sha2::Sha256;
-    type SlowHash = NoOpHash;
-}
-
-pub struct TestVectorParameters {
-    pub client_s_pk: Vec<u8>,
-    pub client_s_sk: Vec<u8>,
-    pub client_e_pk: Vec<u8>,
-    pub client_e_sk: Vec<u8>,
-    pub server_s_pk: Vec<u8>,
-    pub server_s_sk: Vec<u8>,
-    pub server_e_pk: Vec<u8>,
-    pub server_e_sk: Vec<u8>,
-    pub password: Vec<u8>,
-    pub blinding_factor_raw: Vec<u8>,
-    pub blinding_factor: Vec<u8>,
-    pub pepper: Vec<u8>,
-    pub oprf_key: Vec<u8>,
-    pub envelope_nonce: Vec<u8>,
-    pub client_nonce: Vec<u8>,
-    pub server_nonce: Vec<u8>,
-    pub r1: Vec<u8>,
-    pub r2: Vec<u8>,
-    pub r3: Vec<u8>,
-    pub l1: Vec<u8>,
-    pub l2: Vec<u8>,
-    pub l3: Vec<u8>,
-    client_registration_state: Vec<u8>,
-    server_registration_state: Vec<u8>,
-    client_login_state: Vec<u8>,
-    server_login_state: Vec<u8>,
-    pub password_file: Vec<u8>,
-    pub export_key: Vec<u8>,
-    pub shared_secret: Vec<u8>,
-}
-
-static TEST_VECTOR: &str = r#"
-{
-    "client_s_pk": "b2341df425f90244c72d8e19b249ca0d6d1a3a3dfe6ee1773e1b782a81efef29",
-    "client_s_sk": "701e8cd1263abd2f2a22d4dc94b1d5fe3c9cb14030e7e7c154745825b059fd7f",
-    "client_e_pk": "97cb1eb93a69542597517b110ccca457d5ce8d8bfcbfb2a9258bb7b4bd7f716e",
-    "client_e_sk": "80616968ed8daae02c02d3ba41a70104ed0deecd2276e058994d601a1351b359",
-    "server_s_pk": "e12d737e520eaf8504fbf302c2945011bff360bdf02ee102f2ebd6a883c80e02",
-    "server_s_sk": "9075d3d3c5b6bc2f6218e7672c0532c619ce09dddf196006c5ffdaf628a3d760",
-    "server_e_pk": "f73d27d7ca78ded52209bc3bae000f9d95b147360edac1e97c148a3a7396a279",
-    "server_e_sk": "a0e59a07908fc793c590fd83343003a54330e24af908ed31c921e6e6504c3248",
-    "password": "70617373776f7264",
-    "blinding_factor_raw": "ca2d8ae51794579bd0f46044d7daccf222b4590053536b48575bc169f7478fd0a0b580fb0aae948c26ba403a2e7b98f563e434a0aad93f4105419c474453c34e",
-    "blinding_factor": "5a9a073b1a1efedebdb404bc073ae74b316920d68ab628bed0c500cae95d6e02",
-    "pepper": "706570706572",
-    "oprf_key": "203fabe2af9c8dc668b81db1ece9c2412c94c276495f33202479886de1b12907",
-    "envelope_nonce": "b0076712e01fecdb12301d5d7da92236e47f20494e68defb32084f1ab6c3d4f8",
-    "client_nonce": "b9f09e9b0606fa88c4194011d5c204861b73c43cbf1ea0d08c03ec2fd6d05572",
-    "server_nonce": "a213c02274e7f20fc3b571d25e98854c5dae2cfde6c9bf228a66bf3eff3e2a97",
-    "r1": "7e2c67a156ab27490f20008fcae9e9f722d8a9f4eeac373a711259981ca05dd5",
-    "r2": "710fdd19883e869e784c84f2864fa0bfc227662404b77cc8a54d79ae7fb931ea",
-    "r3": "b0076712e01fecdb12301d5d7da92236e47f20494e68defb32084f1ab6c3d4f8923b1d26cac4e3d91cec445b3322f4cc69a727f184353cb4dfe6d55a4c7d2bb4b77fbd41eacb8434f102c8c29cd4831e708046d38615df566675421ae8eb4933b2341df425f90244c72d8e19b249ca0d6d1a3a3dfe6ee1773e1b782a81efef29",
-    "l1": "7e2c67a156ab27490f20008fcae9e9f722d8a9f4eeac373a711259981ca05dd5b9f09e9b0606fa88c4194011d5c204861b73c43cbf1ea0d08c03ec2fd6d0557297cb1eb93a69542597517b110ccca457d5ce8d8bfcbfb2a9258bb7b4bd7f716e",
-    "l2": "710fdd19883e869e784c84f2864fa0bfc227662404b77cc8a54d79ae7fb931eab0076712e01fecdb12301d5d7da92236e47f20494e68defb32084f1ab6c3d4f8923b1d26cac4e3d91cec445b3322f4cc69a727f184353cb4dfe6d55a4c7d2bb4b77fbd41eacb8434f102c8c29cd4831e708046d38615df566675421ae8eb4933a0e59a07908fc793c590fd83343003a54330e24af908ed31c921e6e6504c3248f73d27d7ca78ded52209bc3bae000f9d95b147360edac1e97c148a3a7396a27939ccf2a17a5b281068665b4865e6c6331533461a8e10a4ceffc4c6a6609c326a",
-    "l3": "127144e6469e001d56237a58c8c869a8173e042bf2ff19d8331441d36ada9c3f",
-    "client_registration_state": "5a9a073b1a1efedebdb404bc073ae74b316920d68ab628bed0c500cae95d6e0270617373776f7264",
-    "client_login_state": "5a9a073b1a1efedebdb404bc073ae74b316920d68ab628bed0c500cae95d6e0280616968ed8daae02c02d3ba41a70104ed0deecd2276e058994d601a1351b359b9f09e9b0606fa88c4194011d5c204861b73c43cbf1ea0d08c03ec2fd6d05572f258311568d792d6ebecee225c0fde4512139e29a435e9f9a0b82dc3809a83ab70617373776f7264",
-    "server_registration_state": "203fabe2af9c8dc668b81db1ece9c2412c94c276495f33202479886de1b12907",
-    "server_login_state": "ebc0953924d55ad66aa801a7c85f47f35889b90002451a04fb7134b8a2a5a33cd69098c0a81ce06f58cbe4fd6ba23c9c1404ad6f639ba64d5f0f7bf0a041fc5872b17f13bd41cbfbdfa8d74bc94ec1abcc77b9a3da8fbad918ca0a5f84a81443",
-    "password_file": "203fabe2af9c8dc668b81db1ece9c2412c94c276495f33202479886de1b12907b2341df425f90244c72d8e19b249ca0d6d1a3a3dfe6ee1773e1b782a81efef29b0076712e01fecdb12301d5d7da92236e47f20494e68defb32084f1ab6c3d4f8923b1d26cac4e3d91cec445b3322f4cc69a727f184353cb4dfe6d55a4c7d2bb4b77fbd41eacb8434f102c8c29cd4831e708046d38615df566675421ae8eb4933",
-    "export_key": "da3a52148a58168c9f804df5e216e3d3f16e935d4d70a5eb249433d88e02ae4c",
-    "shared_secret": "72b17f13bd41cbfbdfa8d74bc94ec1abcc77b9a3da8fbad918ca0a5f84a81443"
-}
-"#;
-
-fn decode(values: &Value, key: &str) -> Option<Vec<u8>> {
-    values[key]
-        .as_str()
-        .and_then(|s| hex::decode(&s.to_string()).ok())
-}
-
-fn populate_test_vectors(values: &Value) -> TestVectorParameters {
-    TestVectorParameters {
-        client_s_pk: decode(&values, "client_s_pk").unwrap(),
-        client_s_sk: decode(&values, "client_s_sk").unwrap(),
-        client_e_pk: decode(&values, "client_e_pk").unwrap(),
-        client_e_sk: decode(&values, "client_e_sk").unwrap(),
-        server_s_pk: decode(&values, "server_s_pk").unwrap(),
-        server_s_sk: decode(&values, "server_s_sk").unwrap(),
-        server_e_pk: decode(&values, "server_e_pk").unwrap(),
-        server_e_sk: decode(&values, "server_e_sk").unwrap(),
-        password: decode(&values, "password").unwrap(),
-        blinding_factor_raw: decode(&values, "blinding_factor_raw").unwrap(),
-        blinding_factor: decode(&values, "blinding_factor").unwrap(),
-        pepper: decode(&values, "pepper").unwrap(),
-        oprf_key: decode(&values, "oprf_key").unwrap(),
-        envelope_nonce: decode(&values, "envelope_nonce").unwrap(),
-        client_nonce: decode(&values, "client_nonce").unwrap(),
-        server_nonce: decode(&values, "server_nonce").unwrap(),
-        r1: decode(&values, "r1").unwrap(),
-        r2: decode(&values, "r2").unwrap(),
-        r3: decode(&values, "r3").unwrap(),
-        l1: decode(&values, "l1").unwrap(),
-        l2: decode(&values, "l2").unwrap(),
-        l3: decode(&values, "l3").unwrap(),
-        client_registration_state: decode(&values, "client_registration_state").unwrap(),
-        client_login_state: decode(&values, "client_login_state").unwrap(),
-        server_registration_state: decode(&values, "server_registration_state").unwrap(),
-        server_login_state: decode(&values, "server_login_state").unwrap(),
-        password_file: decode(&values, "password_file").unwrap(),
-        export_key: decode(&values, "export_key").unwrap(),
-        shared_secret: decode(&values, "shared_secret").unwrap(),
-    }
-}
-
-fn stringify_test_vectors(p: &TestVectorParameters) -> String {
-    let mut s = String::new();
-    s.push_str("{\n");
-    s.push_str(format!("\"client_s_pk\": \"{}\",\n", hex::encode(&p.client_s_pk)).as_str());
-    s.push_str(format!("\"client_s_sk\": \"{}\",\n", hex::encode(&p.client_s_sk)).as_str());
-    s.push_str(format!("\"client_e_pk\": \"{}\",\n", hex::encode(&p.client_e_pk)).as_str());
-    s.push_str(format!("\"client_e_sk\": \"{}\",\n", hex::encode(&p.client_e_sk)).as_str());
-    s.push_str(format!("\"server_s_pk\": \"{}\",\n", hex::encode(&p.server_s_pk)).as_str());
-    s.push_str(format!("\"server_s_sk\": \"{}\",\n", hex::encode(&p.server_s_sk)).as_str());
-    s.push_str(format!("\"server_e_pk\": \"{}\",\n", hex::encode(&p.server_e_pk)).as_str());
-    s.push_str(format!("\"server_e_sk\": \"{}\",\n", hex::encode(&p.server_e_sk)).as_str());
-    s.push_str(format!("\"password\": \"{}\",\n", hex::encode(&p.password)).as_str());
-    s.push_str(
-        format!(
-            "\"blinding_factor_raw\": \"{}\",\n",
-            hex::encode(&p.blinding_factor_raw)
-        )
-        .as_str(),
-    );
-    s.push_str(
-        format!(
-            "\"blinding_factor\": \"{}\",\n",
-            hex::encode(&p.blinding_factor)
-        )
-        .as_str(),
-    );
-    s.push_str(format!("\"pepper\": \"{}\",\n", hex::encode(&p.pepper)).as_str());
-    s.push_str(format!("\"oprf_key\": \"{}\",\n", hex::encode(&p.oprf_key)).as_str());
-    s.push_str(
-        format!(
-            "\"envelope_nonce\": \"{}\",\n",
-            hex::encode(&p.envelope_nonce)
-        )
-        .as_str(),
-    );
-    s.push_str(format!("\"client_nonce\": \"{}\",\n", hex::encode(&p.client_nonce)).as_str());
-    s.push_str(format!("\"server_nonce\": \"{}\",\n", hex::encode(&p.server_nonce)).as_str());
-    s.push_str(format!("\"r1\": \"{}\",\n", hex::encode(&p.r1)).as_str());
-    s.push_str(format!("\"r2\": \"{}\",\n", hex::encode(&p.r2)).as_str());
-    s.push_str(format!("\"r3\": \"{}\",\n", hex::encode(&p.r3)).as_str());
-    s.push_str(format!("\"l1\": \"{}\",\n", hex::encode(&p.l1)).as_str());
-    s.push_str(format!("\"l2\": \"{}\",\n", hex::encode(&p.l2)).as_str());
-    s.push_str(format!("\"l3\": \"{}\",\n", hex::encode(&p.l3)).as_str());
-    s.push_str(
-        format!(
-            "\"client_registration_state\": \"{}\",\n",
-            hex::encode(&p.client_registration_state)
-        )
-        .as_str(),
-    );
-    s.push_str(
-        format!(
-            "\"client_login_state\": \"{}\",\n",
-            hex::encode(&p.client_login_state)
-        )
-        .as_str(),
-    );
-    s.push_str(
-        format!(
-            "\"server_registration_state\": \"{}\",\n",
-            hex::encode(&p.server_registration_state)
-        )
-        .as_str(),
-    );
-    s.push_str(
-        format!(
-            "\"server_login_state\": \"{}\",\n",
-            hex::encode(&p.server_login_state)
-        )
-        .as_str(),
-    );
-    s.push_str(
-        format!(
-            "\"password_file\": \"{}\",\n",
-            hex::encode(&p.password_file)
-        )
-        .as_str(),
-    );
-    s.push_str(format!("\"export_key\": \"{}\",\n", hex::encode(&p.export_key)).as_str());
-    s.push_str(format!("\"shared_secret\": \"{}\"\n", hex::encode(&p.shared_secret)).as_str());
-    s.push_str("}\n");
-    s
-}
-
-fn generate_parameters<CS: CipherSuite>() -> TestVectorParameters {
-    let mut rng = OsRng;
-
-    // Inputs
-    let server_s_kp = CS::generate_random_keypair(&mut rng).unwrap();
-    let server_e_kp = CS::generate_random_keypair(&mut rng).unwrap();
-    let client_s_kp = CS::generate_random_keypair(&mut rng).unwrap();
-    let client_e_kp = CS::generate_random_keypair(&mut rng).unwrap();
-    let password = b"password";
-    let pepper = b"pepper";
-    let mut blinding_factor_raw = [0u8; 64];
-    rng.fill_bytes(&mut blinding_factor_raw);
-    let mut oprf_key_raw = [0u8; 32];
-    rng.fill_bytes(&mut oprf_key_raw);
-    let mut envelope_nonce = [0u8; 32];
-    rng.fill_bytes(&mut envelope_nonce);
-    let mut client_nonce = [0u8; NONCE_LEN];
-    rng.fill_bytes(&mut client_nonce);
-    let mut server_nonce = [0u8; NONCE_LEN];
-    rng.fill_bytes(&mut server_nonce);
-
-    let mut blinding_factor_registration_rng = CycleRng::new(blinding_factor_raw.to_vec());
-    let (r1, client_registration) = ClientRegistration::<CS>::start(
-        password,
-        Some(pepper),
-        &mut blinding_factor_registration_rng,
-    )
-    .unwrap();
-    let r1_bytes = r1.to_bytes().to_vec();
-    let blinding_factor_bytes =
-        CS::Group::scalar_as_bytes(&client_registration.blinding_factor).clone();
-    let client_registration_state = client_registration.to_bytes().to_vec();
-
-    let mut oprf_key_rng = CycleRng::new(oprf_key_raw.to_vec());
-    let (r2, server_registration) = ServerRegistration::<CS>::start(r1, &mut oprf_key_rng).unwrap();
-    let r2_bytes = r2.to_bytes().to_vec();
-    let oprf_key_bytes = CS::Group::scalar_as_bytes(&server_registration.oprf_key).clone();
-    let server_registration_state = server_registration.to_bytes().to_vec();
-
-    let mut client_s_sk_and_nonce: Vec<u8> = Vec::new();
-    client_s_sk_and_nonce.extend_from_slice(&client_s_kp.private());
-    client_s_sk_and_nonce.extend_from_slice(&envelope_nonce);
-
-    let mut finish_registration_rng = CycleRng::new(client_s_sk_and_nonce);
-    let (r3, export_key_registration) = client_registration
-        .finish(r2, server_s_kp.public(), &mut finish_registration_rng)
-        .unwrap();
-    let r3_bytes = r3.to_bytes().to_vec();
-
-    let password_file = server_registration.finish(r3).unwrap();
-    let password_file_bytes = password_file.to_bytes();
-
-    let mut client_login_start: Vec<u8> = Vec::new();
-    client_login_start.extend_from_slice(&blinding_factor_raw);
-    client_login_start.extend_from_slice(&client_e_kp.private());
-    client_login_start.extend_from_slice(&client_nonce);
-
-    let mut client_login_start_rng = CycleRng::new(client_login_start);
-    let (l1, client_login) =
-        ClientLogin::<CS>::start(password, Some(pepper), &mut client_login_start_rng).unwrap();
-    let l1_bytes = l1.to_bytes().to_vec();
-    let client_login_state = client_login.to_bytes().to_vec();
-
-    let mut server_e_sk_rng = CycleRng::new(server_e_kp.private().to_vec());
-    let (l2, server_login) = ServerLogin::<CS>::start(
-        password_file,
-        server_s_kp.private(),
-        l1,
-        &mut server_e_sk_rng,
-    )
-    .unwrap();
-    let l2_bytes = l2.to_bytes().to_vec();
-    let server_login_state = server_login.to_bytes().to_vec();
-
-    let mut client_e_sk_rng = CycleRng::new(client_e_kp.private().to_vec());
-    let (l3, client_shared_secret, _export_key_login) = client_login
-        .finish(l2, server_s_kp.public(), &mut client_e_sk_rng)
-        .unwrap();
-    let l3_bytes = l3.to_bytes().to_vec();
-
-    TestVectorParameters {
-        client_s_pk: client_s_kp.public().to_vec(),
-        client_s_sk: client_s_kp.private().to_vec(),
-        client_e_pk: client_e_kp.public().to_vec(),
-        client_e_sk: client_e_kp.private().to_vec(),
-        server_s_pk: server_s_kp.public().to_vec(),
-        server_s_sk: server_s_kp.private().to_vec(),
-        server_e_pk: server_e_kp.public().to_vec(),
-        server_e_sk: server_e_kp.private().to_vec(),
-        password: password.to_vec(),
-        blinding_factor_raw: blinding_factor_raw.to_vec(),
-        blinding_factor: blinding_factor_bytes.to_vec(),
-        pepper: pepper.to_vec(),
-        oprf_key: oprf_key_bytes.to_vec(),
-        envelope_nonce: envelope_nonce.to_vec(),
-        client_nonce: client_nonce.to_vec(),
-        server_nonce: server_nonce.to_vec(),
-        r1: r1_bytes,
-        r2: r2_bytes,
-        r3: r3_bytes,
-        l1: l1_bytes,
-        l2: l2_bytes,
-        l3: l3_bytes,
-        password_file: password_file_bytes,
-        client_registration_state,
-        server_registration_state,
-        client_login_state,
-        server_login_state,
-        shared_secret: client_shared_secret,
-        export_key: export_key_registration.to_vec(),
-    }
-}
-
-#[test]
-fn generate_test_vectors() {
-    let parameters = generate_parameters::<X255193dhNoSlowHash>();
-    println!("{}", stringify_test_vectors(&parameters));
-}
-
-#[test]
-fn test_r1() -> Result<(), PakeError> {
-    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
-    let mut blinding_factor_rng = CycleRng::new(parameters.blinding_factor_raw);
-    let (r1, client_registration) = ClientRegistration::<X255193dhNoSlowHash>::start(
-        &parameters.password,
-        Some(&parameters.pepper),
-        &mut blinding_factor_rng,
-    )
-    .unwrap();
-    assert_eq!(hex::encode(&parameters.r1), hex::encode(r1.to_bytes()));
-    assert_eq!(
-        hex::encode(&parameters.client_registration_state),
-        hex::encode(client_registration.to_bytes())
-    );
-    Ok(())
-}
-
-#[test]
-fn test_r2() -> Result<(), PakeError> {
-    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
-    let mut oprf_key_rng = CycleRng::new(parameters.oprf_key);
-    let (r2, server_registration) = ServerRegistration::<X255193dhNoSlowHash>::start(
-        RegisterFirstMessage::try_from(&parameters.r1[..]).unwrap(),
-        &mut oprf_key_rng,
-    )
-    .unwrap();
-    assert_eq!(hex::encode(parameters.r2), hex::encode(r2.to_bytes()));
-    assert_eq!(
-        hex::encode(&parameters.server_registration_state),
-        hex::encode(server_registration.to_bytes())
-    );
-    Ok(())
-}
-
-#[test]
-fn test_r3() -> Result<(), PakeError> {
-    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
-
-    let client_s_sk_and_nonce: Vec<u8> =
-        [parameters.client_s_sk, parameters.envelope_nonce].concat();
-    let mut finish_registration_rng = CycleRng::new(client_s_sk_and_nonce);
-    let (r3, export_key_registration) = ClientRegistration::<X255193dhNoSlowHash>::try_from(
-        &parameters.client_registration_state[..],
-    )
-    .unwrap()
-    .finish(
-        RegisterSecondMessage::try_from(&parameters.r2[..]).unwrap(),
-        &Key::try_from(&parameters.server_s_pk[..]).unwrap(),
-        &mut finish_registration_rng,
-    )
-    .unwrap();
-
-    assert_eq!(hex::encode(parameters.r3), hex::encode(r3.to_bytes()));
-    assert_eq!(
-        hex::encode(parameters.export_key),
-        hex::encode(export_key_registration.to_vec())
-    );
-
-    Ok(())
-}
-
-#[test]
-fn test_password_file() -> Result<(), PakeError> {
-    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
-
-    let server_registration = ServerRegistration::<X255193dhNoSlowHash>::try_from(
-        &parameters.server_registration_state[..],
-    )
-    .unwrap();
-    let password_file = server_registration
-        .finish(RegisterThirdMessage::try_from(&parameters.r3[..]).unwrap())
-        .unwrap();
-
-    assert_eq!(
-        hex::encode(parameters.password_file),
-        hex::encode(password_file.to_bytes())
-    );
-    Ok(())
-}
-
-#[test]
-fn test_l1() -> Result<(), PakeError> {
-    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
-
-    let client_login_start = [
-        parameters.blinding_factor_raw,
-        parameters.client_e_sk,
-        parameters.client_nonce,
-    ]
-    .concat();
-    let mut client_login_start_rng = CycleRng::new(client_login_start);
-    let (l1, client_login) = ClientLogin::<X255193dhNoSlowHash>::start(
-        &parameters.password,
-        Some(&parameters.pepper),
-        &mut client_login_start_rng,
-    )
-    .unwrap();
-    assert_eq!(hex::encode(&parameters.l1), hex::encode(l1.to_bytes()));
-    assert_eq!(
-        hex::encode(&parameters.client_login_state),
-        hex::encode(client_login.to_bytes())
-    );
-    Ok(())
-}
-
-#[test]
-fn test_l2() -> Result<(), PakeError> {
-    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
-
-    let mut server_e_sk_rng = CycleRng::new(parameters.server_e_sk);
-    let (l2, server_login) = ServerLogin::<X255193dhNoSlowHash>::start(
-        ServerRegistration::try_from(&parameters.password_file[..]).unwrap(),
-        &Key::try_from(&parameters.server_s_sk[..]).unwrap(),
-        LoginFirstMessage::<X255193dhNoSlowHash>::try_from(&parameters.l1[..]).unwrap(),
-        &mut server_e_sk_rng,
-    )
-    .unwrap();
-
-    assert_eq!(hex::encode(&parameters.l2), hex::encode(l2.to_bytes()));
-    assert_eq!(
-        hex::encode(&parameters.server_login_state),
-        hex::encode(server_login.to_bytes())
-    );
-    Ok(())
-}
-
-#[test]
-fn test_l3() -> Result<(), PakeError> {
-    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
-
-    let mut client_e_sk_rng = CycleRng::new(parameters.client_e_sk.to_vec());
-    let (l3, shared_secret, export_key_login) = ClientLogin::<X255193dhNoSlowHash>::try_from(
-        &parameters.client_login_state[..],
-    )
-    .unwrap()
-    .finish(
-        LoginSecondMessage::<EdwardsPoint, X25519KeyPair, TripleDH, sha2::Sha256>::try_from(
-            &parameters.l2[..],
-        )
-        .unwrap(),
-        &Key::try_from(&parameters.server_s_pk[..])?,
-        &mut client_e_sk_rng,
-    )
-    .unwrap();
-
-    assert_eq!(
-        hex::encode(&parameters.shared_secret),
-        hex::encode(&shared_secret)
-    );
-    assert_eq!(hex::encode(&parameters.l3), hex::encode(l3.to_bytes()));
-    assert_eq!(
-        hex::encode(&parameters.export_key),
-        hex::encode(export_key_login)
-    );
-
-    Ok(())
-}
-
-#[test]
-fn test_server_login_finish() -> Result<(), ProtocolError> {
-    let parameters = populate_test_vectors(&serde_json::from_str(TEST_VECTOR).unwrap());
-
-    let shared_secret =
-        ServerLogin::<X255193dhNoSlowHash>::try_from(&parameters.server_login_state[..])
-            .unwrap()
-            .finish(LoginThirdMessage::try_from(&parameters.l3[..])?)
-            .unwrap();
-
-    assert_eq!(
-        hex::encode(parameters.shared_secret),
-        hex::encode(shared_secret)
-    );
-
-    Ok(())
-}
-
-fn test_complete_flow(
-    registration_password: &[u8],
-    login_password: &[u8],
-) -> Result<(), ProtocolError> {
-    let mut client_rng = OsRng;
-    let mut server_rng = OsRng;
-    let server_kp = X255193dhNoSlowHash::generate_random_keypair(&mut server_rng)?;
-    let (register_m1, client_state) = ClientRegistration::<X255193dhNoSlowHash>::start(
-        registration_password,
-        None,
-        &mut client_rng,
-    )?;
-    let (register_m2, server_state) =
-        ServerRegistration::<X255193dhNoSlowHash>::start(register_m1, &mut server_rng)?;
-    let (register_m3, registration_export_key) =
-        client_state.finish(register_m2, server_kp.public(), &mut client_rng)?;
-    let p_file = server_state.finish(register_m3)?;
-    let (login_m1, client_login_state) =
-        ClientLogin::<X255193dhNoSlowHash>::start(login_password, None, &mut client_rng)?;
-    let (login_m2, server_login_state) = ServerLogin::<X255193dhNoSlowHash>::start(
-        p_file,
-        &server_kp.private(),
-        login_m1,
-        &mut server_rng,
-    )?;
-
-    let client_login_result =
-        client_login_state.finish(login_m2, &server_kp.public(), &mut client_rng);
-
-    if hex::encode(registration_password) == hex::encode(login_password) {
-        let (login_m3, client_shared_secret, login_export_key) = client_login_result?;
-        let server_shared_secret = server_login_state.finish(login_m3)?;
-
-        assert_eq!(
-            hex::encode(server_shared_secret),
-            hex::encode(client_shared_secret)
-        );
-        assert_eq!(
-            hex::encode(registration_export_key),
-            hex::encode(login_export_key)
-        );
-    } else {
-        let res = match client_login_result {
-            Err(ProtocolError::VerificationError(PakeError::InvalidLoginError)) => true,
-            _ => false,
-        };
-        assert!(res);
-    }
-
-    Ok(())
-}
-
-#[test]
-fn test_complete_flow_success() -> Result<(), ProtocolError> {
-    test_complete_flow(b"good password", b"good password")
-}
-
-#[test]
-fn test_complete_flow_fail() -> Result<(), ProtocolError> {
-    test_complete_flow(b"good password", b"bad password")
-}

src/tests/opaque_test_vectors.rs

@@ -0,0 +1,583 @@
+// Copyright (c) Facebook, Inc. and its affiliates.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+use crate::{
+    ciphersuite::CipherSuite,
+    errors::*,
+    key_exchange::tripledh::TripleDH,
+    keypair::{Key, SizedBytesExt},
+    opaque::*,
+    slow_hash::NoOpHash,
+    tests::mock_rng::CycleRng,
+    *,
+};
+use curve25519_dalek::ristretto::RistrettoPoint;
+use serde_json::Value;
+
+// Tests
+// =====
+
+struct Ristretto255Sha512NoSlowHash;
+impl CipherSuite for Ristretto255Sha512NoSlowHash {
+    type Group = RistrettoPoint;
+    type KeyExchange = TripleDH;
+    type Hash = sha2::Sha512;
+    type SlowHash = NoOpHash;
+}
+
+#[derive(PartialEq)]
+pub enum EnvelopeMode {
+    Base,
+    CustomIdentifier,
+}
+
+#[allow(non_snake_case)]
+pub struct TestVectorParameters {
+    pub envelope_mode: EnvelopeMode,
+    pub client_public_key: Vec<u8>,
+    pub client_private_key: Vec<u8>,
+    pub client_keyshare: Vec<u8>,
+    pub client_private_keyshare: Vec<u8>,
+    pub server_public_key: Vec<u8>,
+    pub server_private_key: Vec<u8>,
+    pub server_keyshare: Vec<u8>,
+    pub server_private_keyshare: Vec<u8>,
+    pub client_identity: Vec<u8>,
+    pub server_identity: Vec<u8>,
+    pub password: Vec<u8>,
+    pub blind_registration: Vec<u8>,
+    pub oprf_key: Vec<u8>,
+    pub envelope_nonce: Vec<u8>,
+    pub client_nonce: Vec<u8>,
+    pub server_nonce: Vec<u8>,
+    pub client_info: Vec<u8>,
+    pub server_info: Vec<u8>,
+    pub registration_request: Vec<u8>,
+    pub registration_response: Vec<u8>,
+    pub registration_upload: Vec<u8>,
+    pub KE1: Vec<u8>,
+    pub blind_login: Vec<u8>,
+    pub KE2: Vec<u8>,
+    pub KE3: Vec<u8>,
+    pub export_key: Vec<u8>,
+    pub session_key: Vec<u8>,
+}
+
+// Pulled from "OPAQUE-3DH Test Vector 1" and "OPAQUE-3DH Test Vector 6"
+// of https://datatracker.ietf.org/doc/draft-irtf-cfrg-opaque/
+static TEST_VECTORS: &[&str] = &[
+    r#"
+OPRF: 0001
+Hash: SHA512
+SlowHash: Identity
+EnvelopeMode: 01
+Group: ristretto255
+Nh: 64
+Npk: 32
+Nsk: 32
+password: 436f7272656374486f72736542617474657279537461706c65
+envelope_nonce: cc7abb200199d5071c94efa49fb62435d3e70d03cf9573a95da54
+20d3eebcd2b
+client_private_key: 8bcb0b70dac18de24eef12e737d6b28724d3e37774e0b092f
+9f70b255defaf04
+client_public_key: 360e716c676cfe4d9968d1a352ed3faf17603863e0a7aa1905
+df6ea129343b09
+server_private_key: f3a0829898a89239dce29ccc98ec8b449a34b255ba1e6f944
+829d18e0d589b0f
+server_public_key: 66e130c6eb5b41f851b235b03a0eafeaa883f64147bc62cb74
+9c22c762389c3c
+client_info: 68656c6c6f20626f62
+server_info: 6772656574696e677320616c696365
+server_nonce: 98b8081059f60ffed9336f026fd8e124737205ac73f5348ae5bebdb
+49456c70f
+client_nonce: 58dc21475ff730342f807bf031c7ae47a11f0d4dfaa63a7feb15d7e
+36427ca44
+server_keyshare: 5214e3ddc73db786480b79fa2da787f2080b82cbe922c2a9592b
+44597d9a702e
+client_keyshare: a4084c7296b1a3d5a5e4a24358750489575acfd8fcfa6e787492
+b98265a5e651
+server_private_keyshare: c4d002aa4cfcf281657cf36fe562bc60d9133e0e72a7
+4432f685b2b6a4b42a0c
+client_private_keyshare: de2e98f422bf7b99be19f7da7cac62f1599d35a225ec
+6340149a0aaff3102003
+blind_registration: 7e5bcbf82a46109ee0d24e9bcab41fc830a6ce8b82fc1e921
+3a043b743b95800
+blind_login: c4d5a15f0d5ffc354e340454ec779f575e4573a3886ab5e57e4da298
+4bdd5306
+oprf_key: 080d0a4d352de92672ab709b1ae1888cb48dfabc2d6ca5b914b335512fe
+70508
+auth_key: 7bb7f2b831ee30d3e5cc4012c8f721a4d8f9dd494932d53776e043df9bd
+2aa284025b8b006fd8449536446ff50698f46c73fccb53f20d80898f185307d1d39e5
+prk: b0aefddbb21d1b97bc40c07b172e0bf172ec740de4f6274f69d46350a447e9b1
+b3fb1e4cefc7d8e393ff58a5c45c74d0615ee0eecde116f3d4e744142eb2ee89
+pseudorandom_pad: 36a828b3b57bf242c4c47ccd9cb84e5b3cefaffe09629c6b94d
+eba0ccec5fa39
+envelope: 01cc7abb200199d5071c94efa49fb62435d3e70d03cf9573a95da5420d3
+eebcd2bbd6323c36fba7fa08a2b6e2aab6efcdc183c4c897d822cf96d29b129932a55
+3d469ffa9999fcbd37a1e8b6c1e579bcf83fed355c9ff413e6158d72d16f3ccd8699e
+906027842694b6293b6303bbb7f324e0fccb4ae0f01edb60ee1d32992696e
+handshake_secret: 2b041dcf12ac9b75dded88f891c25d76746ce9e2c1a43118ac4
+aa5721cdc1bc2f0691e6c012a1ea9eb95ab4899b3e7058d37fe9546c46b0511877e40
+f55aac6c
+handshake_encrypt_key: ceef10f15d869a4cea8174fa98d0d96c7aaf8602d006fe
+0c5274a40173db76cac820138c5890bb63fb974d1e3e925850cc2464e2c10f0a9a776
+9a45e80889b1e
+server_mac_key: f8fd7fdc349b5ae1339515e05912c89a795f561a117cdc84d8d8b
+5f05b05751abfb87fa01c799c5d367244d1e32eab67ff926833c6025c556acffa4af1
+f3871a
+client_mac_key: 92a30cc82c374c06895aa07e81f0cf5f25309a24b595faefcd225
+1f9219b47e47d17da4fe8b572dedefa350ed365f87b217973e90d0b647a2ccf1d796a
+8970f6
+registration_request: ec9027daa5e9a901d641286a7ded51364142936ac7636e1
+42e3f4368b4bd8124
+registration_response: 8867d7c8c2c576a6322d49d46078ea32f479aed917c70a
+636d3ada4397ea1c0e66e130c6eb5b41f851b235b03a0eafeaa883f64147bc62cb749
+c22c762389c3c
+registration_upload: 360e716c676cfe4d9968d1a352ed3faf17603863e0a7aa19
+05df6ea129343b0901cc7abb200199d5071c94efa49fb62435d3e70d03cf9573a95da
+5420d3eebcd2bbd6323c36fba7fa08a2b6e2aab6efcdc183c4c897d822cf96d29b129
+932a553d469ffa9999fcbd37a1e8b6c1e579bcf83fed355c9ff413e6158d72d16f3cc
+d8699e906027842694b6293b6303bbb7f324e0fccb4ae0f01edb60ee1d32992696e
+KE1: e06a32011e1b1704eb686b263e5d132fff4e9f6429cd93b98db107485006792c
+58dc21475ff730342f807bf031c7ae47a11f0d4dfaa63a7feb15d7e36427ca4400096
+8656c6c6f20626f62a4084c7296b1a3d5a5e4a24358750489575acfd8fcfa6e787492
+b98265a5e651
+KE2: 66f6b5fa1a4eb6bd7a0c93ed2639a31cba0d02e2df744003641d5a30a4a12364
+66e130c6eb5b41f851b235b03a0eafeaa883f64147bc62cb749c22c762389c3c01cc7
+abb200199d5071c94efa49fb62435d3e70d03cf9573a95da5420d3eebcd2bbd6323c3
+6fba7fa08a2b6e2aab6efcdc183c4c897d822cf96d29b129932a553d469ffa9999fcb
+d37a1e8b6c1e579bcf83fed355c9ff413e6158d72d16f3ccd8699e906027842694b62
+93b6303bbb7f324e0fccb4ae0f01edb60ee1d32992696e98b8081059f60ffed9336f0
+26fd8e124737205ac73f5348ae5bebdb49456c70f5214e3ddc73db786480b79fa2da7
+87f2080b82cbe922c2a9592b44597d9a702e000f72f38a0945819089c44c86820c51d
+89cc35f77df03d330101bbed3b2f69066112f32529bdda0998657350fc9f8da4cde73
+408ad931f4c2ea6237ccae4696483388b174f50cf96d439139b0f8680c3b
+KE3: 9f0e4f73455ca9fe06bb52ad02670b09be5a03db11a73be4422f19963be082b0
+eb55871022e8d1d87adc3ab50de7c738058eb659866d091648f2fed12e23fd53
+export_key: 66c0b72aa829f13a166fb1a1168f1e26023921f0eed1126def4f81ba0
+4924ad6012e42b63656ec199ba27670d1e7f23dc0a927714edc140134dde5a5d2063d
+fc
+session_key: 951c2bb1b876725fa7d3829db791dddd406a688507b47e24101bd0cc
+5d071760b6fba59e8758a6ea6d7e5f51a715b49a47c50fee9a7c8a0451243c3ee837f
+d30
+"#,
+    r#"
+OPRF: 0001
+Hash: SHA512
+SlowHash: Identity
+EnvelopeMode: 02
+Group: ristretto255
+Nh: 64
+Npk: 32
+Nsk: 32
+client_identity: 20fa92f2e4b7ea5b5e677ac4930ff3b93b0043481ab70bc613b2
+e16a6dde6b05
+server_identity: eae9dfa6b8348d34418c32d385e1eac99efbce1af320901f7c8e
+de8d6d272c65
+password: 436f7272656374486f72736542617474657279537461706c65
+envelope_nonce: f41e8b3c5a999aa946f9b562a150e5c5e36748a31a79feb241809
+0438877888c
+client_private_key: dc70a99bbabf1ebe98b192e93cedceb9c0164e95b891bd8bc
+81721b83d66b00b
+client_public_key: 20fa92f2e4b7ea5b5e677ac4930ff3b93b0043481ab70bc613
+b2e16a6dde6b05
+server_private_key: 709687a36c94592ab76579f42ce1be6961f0700496e71df80
+6ebd5320554720d
+server_public_key: eae9dfa6b8348d34418c32d385e1eac99efbce1af320901f7c
+8ede8d6d272c65
+client_info: 68656c6c6f20626f62
+server_info: 6772656574696e677320616c696365
+server_nonce: ef49d83cef5f1411ea30abb82b08bd85423aadb86e2c19df5930b3c
+8498b9f97
+client_nonce: 4ab1227db632bc079f79c0f5279df2dfa75cfbd4434ab40dcf844d6
+77165cd3b
+server_keyshare: 96a9587e233e67f2397f10fec6355b68102534f1f1b115b4ddf7
+485840efcd7c
+client_keyshare: 54f35db3a52fb0cf2a97918a6987993231d227e28711eaef19a3
+e5033632611a
+server_private_keyshare: 6650d64df70618a878504ce73dcca27b1af125c67e48
+1e7bd49d0b24709b200f
+client_private_keyshare: ebb01c59f99bc955df622548e247f7ef180732909ff3
+c5f87ff8c7867b8be704
+blind_registration: 308f1d3fa1fea402f3c90b04601274050a3c6f467387c2f48
+878823949b0e109
+blind_login: 141e21373228a44b09d4c00da9a6bbaf9a5e54a1687c07f327833643
+4245510b
+oprf_key: b7126967aa0cb69c311b71343843ea041bae30e2bde41b548b8fbd8bced
+97604
+auth_key: 9f761a5a56a74269b382403aeba47c1d24b9e200e1839efcb616fb280da
+1b6ba7bd71d6455dd3cd979c545608cfbfc1c4e9ba677e1d40848054a00696c4b2589
+prk: 30bc3f37a757890ac17ce46043f3c5ed30c96fb8743205e77e84dc167d98e114
+6093150ff7b4d002f793bfe717e88d174ed2669abdd9e96af473a7ac82973b0a
+pseudorandom_pad: b909f990c94b9c5949a2b8d0874d602f846b7981b331fd79978
+b530cc46c8670
+envelope: 02f41e8b3c5a999aa946f9b562a150e5c5e36748a31a79feb2418090438
+877888c6579500b73f482e7d1132a39bba0ae96447d37140ba040f25f9c72b4f90a36
+7bdb425fa1dd4c49e17780f33b821e1e019668fe7f45520e26996ac8cb08e3d2566cc
+439c83030464effecb8350e7b1ca31087d87f6a45ed3910c185a24a89d282
+handshake_secret: ff89f264f8c3974238f4c8d736af7b0a55f2e4edc487cbf3e5c
+7b4bbf21acd7c1d28354c2c8555fba57c4d4b1fbb4b772bfdf909881f67dd517cc9f4
+f6ebaeac
+handshake_encrypt_key: 3071b181f639062cf70b74d0ffe5ec8fa695da13cd2f00
+e74b8b7ef348ae7a5df9c3a32c9f7aeaad5a28379712cf849b9707e221dce124abfad
+d0225a8e8e045
+server_mac_key: 7c37b344d189cbbeff80bbb4b78e2703d1a80dc28239923094287
+62f7ce2a93b11f6e85dd45c02809afe8583d4aad6377e72788773af92eef33c690692
+20ae76
+client_mac_key: 2c4aff12ba7aa911a51f9e5b7a7c01439d854c97e4b8ec842a9db
+d78345760328fd5a72424e49e25ec8fe1b6d9d42f774516f400948bd5a105d995d000
+2fc83b
+registration_request: 3c8b89966e261a5aaf7aeb6dcdd94c87ce311bf197221b8
+7ef44632d58f18a05
+registration_response: caf9243d7ef3e267815632bf79c85a27a23f218a438815
+2a523f6a310949807beae9dfa6b8348d34418c32d385e1eac99efbce1af320901f7c8
+ede8d6d272c65
+registration_upload: 20fa92f2e4b7ea5b5e677ac4930ff3b93b0043481ab70bc6
+13b2e16a6dde6b0502f41e8b3c5a999aa946f9b562a150e5c5e36748a31a79feb2418
+090438877888c6579500b73f482e7d1132a39bba0ae96447d37140ba040f25f9c72b4
+f90a367bdb425fa1dd4c49e17780f33b821e1e019668fe7f45520e26996ac8cb08e3d
+2566cc439c83030464effecb8350e7b1ca31087d87f6a45ed3910c185a24a89d282
+KE1: 8261a1efd78bea73faf256a23c200d729259886530fa43b875c1ca124b09bc7e
+4ab1227db632bc079f79c0f5279df2dfa75cfbd4434ab40dcf844d677165cd3b00096
+8656c6c6f20626f6254f35db3a52fb0cf2a97918a6987993231d227e28711eaef19a3
+e5033632611a
+KE2: fa1f33a43a03123ebe35345ef93aa23b57ea8bfbee7022b05a179d60768ba02e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: d81f93397cdba85a43993d4d9afbdc67f147adfa2b223213b19692cb820eef48
+5073eda4c8236b2f47702404ad60d9a875d189626fc7b7cc861825385470ae54
+export_key: 03192555940b5b42e64e6200bf55cc701f1bace3d402a2f8d83977843
+51a1e3fa1f07a471b783b208acb1d92be47903b6fa3a0df9f4d4b7956ee4f431e2950
+f6
+session_key: 58a7fa98bf3b7b52da21406abfb11d98734354edd47d7b32462c0513
+f0617c89824ea6031d4147a86fc9f6c6837ce640c12fb937d764f296d1a9421ad1b2a
+5d5
+"#,
+];
+
+macro_rules! parse {
+    ( $v:ident, $s:expr ) => {
+        match decode(&$v, $s) {
+            Some(x) => x,
+            None => vec![],
+        }
+    };
+}
+
+macro_rules! rfc_to_params {
+    ( $v:ident ) => {
+        $v.iter()
+            .map(|x| populate_test_vectors(&serde_json::from_str(rfc_to_json(x).as_str()).unwrap()))
+            .collect::<Vec<TestVectorParameters>>()
+    };
+}
+
+fn rfc_to_json(input: &str) -> String {
+    let mut json = vec![];
+    for line in input.lines() {
+        // If line contains colon, then
+        if line.contains(":") {
+            if json.len() > 0 {
+                // Adding closing quote for previous line, comma, and newline
+                json.push("\",\n".to_string());
+            }
+
+            let mut iter = line.split(":");
+            let key = iter.next().unwrap().split_whitespace().next().unwrap();
+            let val = iter.next().unwrap().split_whitespace().next().unwrap();
+
+            json.push(format!("    \"{}\": \"{}", key, val));
+        } else {
+            let s = line.trim().to_string();
+            if s.len() > 0 {
+                json.push(s);
+            }
+        }
+    }
+
+    format!("{{\n{}\"\n}}", json.join(""))
+}
+
+fn decode(values: &Value, key: &str) -> Option<Vec<u8>> {
+    values[key]
+        .as_str()
+        .and_then(|s| hex::decode(&s.to_string()).ok())
+}
+
+fn populate_test_vectors(values: &Value) -> TestVectorParameters {
+    TestVectorParameters {
+        envelope_mode: match values["EnvelopeMode"].as_str() {
+            Some("01") => EnvelopeMode::Base,
+            Some("02") => EnvelopeMode::CustomIdentifier,
+            _ => panic!("Could not match envelope mode"),
+        },
+        client_public_key: parse!(values, "client_public_key"),
+        client_private_key: parse!(values, "client_private_key"),
+        client_keyshare: parse!(values, "client_keyshare"),
+        client_private_keyshare: parse!(values, "client_private_keyshare"),
+        server_public_key: parse!(values, "server_public_key"),
+        server_private_key: parse!(values, "server_private_key"),
+        server_keyshare: parse!(values, "server_keyshare"),
+        server_private_keyshare: parse!(values, "server_private_keyshare"),
+        client_identity: parse!(values, "client_identity"),
+        server_identity: parse!(values, "server_identity"),
+        password: parse!(values, "password"),
+        blind_registration: parse!(values, "blind_registration"),
+        oprf_key: parse!(values, "oprf_key"),
+        envelope_nonce: parse!(values, "envelope_nonce"),
+        client_nonce: parse!(values, "client_nonce"),
+        server_nonce: parse!(values, "server_nonce"),
+        client_info: parse!(values, "client_info"),
+        server_info: parse!(values, "server_info"),
+        registration_request: parse!(values, "registration_request"),
+        registration_response: parse!(values, "registration_response"),
+        registration_upload: parse!(values, "registration_upload"),
+        KE1: parse!(values, "KE1"),
+        KE2: parse!(values, "KE2"),
+        KE3: parse!(values, "KE3"),
+        blind_login: parse!(values, "blind_login"),
+        export_key: parse!(values, "export_key"),
+        session_key: parse!(values, "session_key"),
+    }
+}
+
+fn get_password_file_bytes(parameters: &TestVectorParameters) -> Result<Vec<u8>, ProtocolError> {
+    let mut oprf_key_rng = CycleRng::new(parameters.oprf_key.clone());
+    let server_registration_start_result =
+        ServerRegistration::<Ristretto255Sha512NoSlowHash>::start(
+            &mut oprf_key_rng,
+            RegistrationRequest::deserialize(&parameters.registration_request[..]).unwrap(),
+            &Key::from_bytes(&parameters.server_public_key[..]).unwrap(),
+        )?;
+
+    let password_file = server_registration_start_result
+        .state
+        .finish(RegistrationUpload::deserialize(&parameters.registration_upload[..]).unwrap())?;
+
+    Ok(password_file.serialize())
+}
+
+#[test]
+fn test_registration_request() -> Result<(), ProtocolError> {
+    for parameters in rfc_to_params!(TEST_VECTORS) {
+        let mut rng = CycleRng::new(parameters.blind_registration.to_vec());
+        let client_registration_start_result =
+            ClientRegistration::<Ristretto255Sha512NoSlowHash>::start(
+                &mut rng,
+                &parameters.password,
+            )?;
+        assert_eq!(
+            hex::encode(&parameters.registration_request),
+            hex::encode(client_registration_start_result.message.serialize())
+        );
+    }
+    Ok(())
+}
+
+#[test]
+fn test_registration_response() -> Result<(), ProtocolError> {
+    for parameters in rfc_to_params!(TEST_VECTORS) {
+        let mut oprf_key_rng = CycleRng::new(parameters.oprf_key);
+        let server_registration_start_result =
+            ServerRegistration::<Ristretto255Sha512NoSlowHash>::start(
+                &mut oprf_key_rng,
+                RegistrationRequest::deserialize(&parameters.registration_request[..]).unwrap(),
+                &Key::from_bytes(&parameters.server_public_key[..]).unwrap(),
+            )?;
+        assert_eq!(
+            hex::encode(parameters.registration_response),
+            hex::encode(server_registration_start_result.message.serialize())
+        );
+    }
+    Ok(())
+}
+
+#[test]
+fn test_registration_upload() -> Result<(), ProtocolError> {
+    for parameters in rfc_to_params!(TEST_VECTORS) {
+        let mut rng = CycleRng::new(parameters.blind_registration.to_vec());
+        let client_registration_start_result =
+            ClientRegistration::<Ristretto255Sha512NoSlowHash>::start(
+                &mut rng,
+                &parameters.password,
+            )?;
+
+        let sk_u_and_nonce: Vec<u8> =
+            [parameters.client_private_key, parameters.envelope_nonce].concat();
+        let mut finish_registration_rng = CycleRng::new(sk_u_and_nonce);
+        let result = client_registration_start_result.state.finish(
+            &mut finish_registration_rng,
+            RegistrationResponse::deserialize(&parameters.registration_response[..]).unwrap(),
+            if parameters.envelope_mode == EnvelopeMode::CustomIdentifier {
+                ClientRegistrationFinishParameters::WithIdentifiers(
+                    parameters.client_identity,
+                    parameters.server_identity,
+                )
+            } else {
+                ClientRegistrationFinishParameters::default()
+            },
+        )?;
+
+        assert_eq!(
+            hex::encode(parameters.registration_upload),
+            hex::encode(result.message.serialize())
+        );
+        assert_eq!(
+            hex::encode(parameters.export_key),
+            hex::encode(result.export_key.to_vec())
+        );
+    }
+
+    Ok(())
+}
+
+#[test]
+fn test_ke1() -> Result<(), ProtocolError> {
+    for parameters in rfc_to_params!(TEST_VECTORS) {
+        let client_login_start = [
+            parameters.blind_login,
+            parameters.client_private_keyshare,
+            parameters.client_nonce,
+        ]
+        .concat();
+        let mut client_login_start_rng = CycleRng::new(client_login_start);
+        let client_login_start_result = ClientLogin::<Ristretto255Sha512NoSlowHash>::start(
+            &mut client_login_start_rng,
+            &parameters.password,
+            ClientLoginStartParameters::WithInfo(parameters.client_info),
+        )?;
+        assert_eq!(
+            hex::encode(&parameters.KE1),
+            hex::encode(client_login_start_result.message.serialize())
+        );
+    }
+    Ok(())
+}
+
+#[test]
+fn test_ke2() -> Result<(), ProtocolError> {
+    for parameters in rfc_to_params!(TEST_VECTORS) {
+        let password_file_bytes = get_password_file_bytes(&parameters)?;
+
+        let mut server_private_keyshare_and_nonce_rng =
+            CycleRng::new([parameters.server_private_keyshare, parameters.server_nonce].concat());
+        let server_login_start_result = ServerLogin::<Ristretto255Sha512NoSlowHash>::start(
+            &mut server_private_keyshare_and_nonce_rng,
+            ServerRegistration::deserialize(&password_file_bytes[..]).unwrap(),
+            &Key::from_bytes(&parameters.server_private_key[..]).unwrap(),
+            CredentialRequest::<Ristretto255Sha512NoSlowHash>::deserialize(&parameters.KE1[..])
+                .unwrap(),
+            if parameters.envelope_mode == EnvelopeMode::CustomIdentifier {
+                ServerLoginStartParameters::WithInfoAndIdentifiers(
+                    parameters.server_info.to_vec(),
+                    parameters.client_identity,
+                    parameters.server_identity,
+                )
+            } else {
+                ServerLoginStartParameters::WithInfo(parameters.server_info.to_vec())
+            },
+        )?;
+        assert_eq!(
+            hex::encode(&parameters.client_info),
+            hex::encode(server_login_start_result.plain_info),
+        );
+        assert_eq!(
+            hex::encode(&parameters.KE2),
+            hex::encode(server_login_start_result.message.serialize())
+        );
+    }
+    Ok(())
+}
+
+#[test]
+fn test_ke3() -> Result<(), ProtocolError> {
+    for parameters in rfc_to_params!(TEST_VECTORS) {
+        let client_login_start = [
+            parameters.blind_login,
+            parameters.client_private_keyshare,
+            parameters.client_nonce,
+        ]
+        .concat();
+        let mut client_login_start_rng = CycleRng::new(client_login_start);
+        let client_login_start_result = ClientLogin::<Ristretto255Sha512NoSlowHash>::start(
+            &mut client_login_start_rng,
+            &parameters.password,
+            ClientLoginStartParameters::WithInfo(parameters.client_info),
+        )?;
+
+        let client_login_finish_result = client_login_start_result.state.finish(
+            CredentialResponse::<Ristretto255Sha512NoSlowHash>::deserialize(&parameters.KE2[..])?,
+            if parameters.envelope_mode == EnvelopeMode::CustomIdentifier {
+                ClientLoginFinishParameters::WithIdentifiers(
+                    parameters.client_identity,
+                    parameters.server_identity,
+                )
+            } else {
+                ClientLoginFinishParameters::default()
+            },
+        )?;
+
+        assert_eq!(
+            hex::encode(&parameters.server_info),
+            hex::encode(&client_login_finish_result.confidential_info)
+        );
+        assert_eq!(
+            hex::encode(&parameters.session_key),
+            hex::encode(&client_login_finish_result.session_key)
+        );
+        assert_eq!(
+            hex::encode(&parameters.KE3),
+            hex::encode(client_login_finish_result.message.serialize())
+        );
+        assert_eq!(
+            hex::encode(&parameters.export_key),
+            hex::encode(client_login_finish_result.export_key)
+        );
+    }
+    Ok(())
+}
+
+#[test]
+fn test_server_login_finish() -> Result<(), ProtocolError> {
+    for parameters in rfc_to_params!(TEST_VECTORS) {
+        let password_file_bytes = get_password_file_bytes(&parameters)?;
+
+        let mut server_private_keyshare_and_nonce_rng =
+            CycleRng::new([parameters.server_private_keyshare, parameters.server_nonce].concat());
+        let server_login_start_result = ServerLogin::<Ristretto255Sha512NoSlowHash>::start(
+            &mut server_private_keyshare_and_nonce_rng,
+            ServerRegistration::deserialize(&password_file_bytes[..]).unwrap(),
+            &Key::from_bytes(&parameters.server_private_key[..]).unwrap(),
+            CredentialRequest::<Ristretto255Sha512NoSlowHash>::deserialize(&parameters.KE1[..])
+                .unwrap(),
+            if parameters.envelope_mode == EnvelopeMode::CustomIdentifier {
+                ServerLoginStartParameters::WithInfoAndIdentifiers(
+                    parameters.server_info.to_vec(),
+                    parameters.client_identity,
+                    parameters.server_identity,
+                )
+            } else {
+                ServerLoginStartParameters::WithInfo(parameters.server_info.to_vec())
+            },
+        )?;
+
+        let server_login_result = server_login_start_result
+            .state
+            .finish(CredentialFinalization::deserialize(&parameters.KE3[..])?)?;
+
+        assert_eq!(
+            hex::encode(parameters.session_key),
+            hex::encode(server_login_result.session_key)
+        );
+    }
+    Ok(())
+}

src/tests/serialization.rs

@@ -1,228 +0,0 @@
-// Copyright (c) Facebook, Inc. and its affiliates.
-//
-// This source code is licensed under the MIT license found in the
-// LICENSE file in the root directory of this source tree.
-
-use crate::{
-    ciphersuite::CipherSuite,
-    envelope::Envelope,
-    group::Group,
-    key_exchange::{
-        traits::{KeyExchange, ToBytes},
-        tripledh::{TripleDH, NONCE_LEN},
-    },
-    keypair::{KeyPair, SizedBytes, X25519KeyPair},
-    opaque::*,
-};
-
-use curve25519_dalek::ristretto::RistrettoPoint;
-use generic_array::typenum::Unsigned;
-use proptest::{collection::vec, prelude::*};
-use rand_core::{OsRng, RngCore};
-
-use sha2::{Digest, Sha256};
-use std::convert::TryFrom;
-
-struct Default;
-impl CipherSuite for Default {
-    type Group = RistrettoPoint;
-    type KeyFormat = crate::keypair::X25519KeyPair;
-    type KeyExchange = TripleDH;
-    type Hash = sha2::Sha256;
-    type SlowHash = crate::slow_hash::NoOpHash;
-}
-
-fn random_ristretto_point() -> RistrettoPoint {
-    let mut rng = OsRng;
-    let mut random_bits = [0u8; 64];
-    rng.fill_bytes(&mut random_bits);
-
-    // This is because RistrettoPoint is on an obsolete sha2 version
-    let mut bits = [0u8; 64];
-    let mut hasher = sha2::Sha512::new();
-    hasher.update(&random_bits[..]);
-    bits.copy_from_slice(&hasher.finalize());
-
-    RistrettoPoint::from_uniform_bytes(&bits)
-}
-
-#[test]
-fn client_registration_roundtrip() {
-    let pw = b"hunter2";
-    let mut rng = OsRng;
-    let sc = <RistrettoPoint as Group>::random_scalar(&mut rng);
-    // serialization order: scalar, password
-    let bytes: Vec<u8> = [&sc.as_bytes()[..], &pw[..]].concat();
-    let reg = ClientRegistration::<Default>::try_from(&bytes[..]).unwrap();
-    let reg_bytes = reg.to_bytes();
-    assert_eq!(reg_bytes, bytes);
-}
-
-#[test]
-fn server_registration_roundtrip() {
-    // If we don't have envelope and client_pk, the server registration just
-    // contains the prf key
-    let mut rng = OsRng;
-    let sc = <RistrettoPoint as Group>::random_scalar(&mut rng);
-    let mut oprf_bytes: Vec<u8> = vec![];
-    oprf_bytes.extend_from_slice(sc.as_bytes());
-    let reg = ServerRegistration::<Default>::try_from(&oprf_bytes[..]).unwrap();
-    let reg_bytes = reg.to_bytes();
-    assert_eq!(reg_bytes, oprf_bytes);
-    // If we do have envelope and client pk, the server registration contains
-    // the whole kit
-    let key_len =
-        <<<Default as CipherSuite>::KeyFormat as KeyPair>::Repr as SizedBytes>::Len::to_usize();
-    let envelope_size = key_len + Envelope::<sha2::Sha256>::additional_size();
-    let mut mock_envelope_bytes = vec![0u8; envelope_size];
-    rng.fill_bytes(&mut mock_envelope_bytes);
-    println!("{}", mock_envelope_bytes.len());
-    let mock_client_kp = Default::generate_random_keypair(&mut rng).unwrap();
-    // serialization order: scalar, public key, envelope
-    let mut bytes = Vec::<u8>::new();
-    bytes.extend_from_slice(sc.as_bytes());
-    bytes.extend_from_slice(&mock_client_kp.public().to_arr());
-    bytes.extend_from_slice(&mock_envelope_bytes);
-    let reg = ServerRegistration::<Default>::try_from(&bytes[..]).unwrap();
-    let reg_bytes = reg.to_bytes();
-    assert_eq!(reg_bytes, bytes);
-}
-
-#[test]
-fn register_first_message_roundtrip() {
-    let pt = random_ristretto_point();
-    let pt_bytes = pt.to_arr();
-    let r1 = RegisterFirstMessage::<RistrettoPoint>::try_from(pt_bytes.as_slice()).unwrap();
-    let r1_bytes = r1.to_bytes();
-    assert_eq!(pt_bytes, r1_bytes);
-}
-
-#[test]
-fn register_second_message_roundtrip() {
-    let pt = random_ristretto_point();
-    let pt_bytes = pt.to_arr();
-
-    let message = pt_bytes.to_vec();
-    let r2 = RegisterSecondMessage::<RistrettoPoint>::try_from(&message[..]).unwrap();
-    let r2_bytes = r2.to_bytes();
-    assert_eq!(message, r2_bytes);
-}
-
-#[test]
-fn register_third_message_roundtrip() {
-    let mut rng = OsRng;
-    let skp = Default::generate_random_keypair(&mut rng).unwrap();
-    let pubkey_bytes = skp.public().to_arr();
-
-    let mut key = [0u8; 32];
-    rng.fill_bytes(&mut key);
-
-    let mut msg = [0u8; 32];
-    rng.fill_bytes(&mut msg);
-
-    let (ciphertext, _) =
-        Envelope::<sha2::Sha256>::seal(&key, &msg, &pubkey_bytes, &mut rng).unwrap();
-
-    let message: Vec<u8> = [&ciphertext.to_bytes(), &pubkey_bytes[..]].concat();
-    let r3 = RegisterThirdMessage::<X25519KeyPair, sha2::Sha256>::try_from(&message[..]).unwrap();
-    let r3_bytes = r3.to_bytes();
-    assert_eq!(message, r3_bytes);
-}
-
-#[test]
-fn client_login_roundtrip() {
-    let pw = b"hunter2";
-    let mut rng = OsRng;
-    let sc = <RistrettoPoint as Group>::random_scalar(&mut rng);
-
-    let client_e_kp = Default::generate_random_keypair(&mut rng).unwrap();
-    let mut client_nonce = [0u8; NONCE_LEN];
-    rng.fill_bytes(&mut client_nonce);
-
-    let l1_data = [&sc.to_bytes()[..], &client_nonce, client_e_kp.public()].concat();
-    let mut hasher = Sha256::new();
-    hasher.update(l1_data);
-    let hashed_l1 = hasher.finalize();
-
-    // serialization order: scalar, password, ke1_state
-    let bytes: Vec<u8> = [
-        &sc.as_bytes()[..],
-        &pw[..],
-        client_e_kp.public(),
-        &client_nonce,
-        hashed_l1.as_slice(),
-    ]
-    .concat();
-    let reg = ClientLogin::<Default>::try_from(&bytes[..]).unwrap();
-    let reg_bytes = reg.to_bytes();
-    assert_eq!(reg_bytes, bytes);
-}
-
-#[test]
-fn login_first_message_roundtrip() {
-    let mut rng = OsRng;
-
-    let client_e_kp = Default::generate_random_keypair(&mut rng).unwrap();
-    let mut client_nonce = [0u8; NONCE_LEN];
-    rng.fill_bytes(&mut client_nonce);
-
-    let ke1m: Vec<u8> = [&client_nonce[..], &client_e_kp.public()].concat();
-    let reg =
-        <TripleDH as KeyExchange<sha2::Sha256>>::KE1Message::try_from(ke1m[..].to_vec()).unwrap();
-    let reg_bytes = reg.to_bytes();
-    assert_eq!(reg_bytes, ke1m);
-}
-
-proptest! {
-
-    #[test]
-    fn test_nocrash_register_first_message(bytes in vec(any::<u8>(), 0..200)) {
-        RegisterFirstMessage::<RistrettoPoint>::try_from(&bytes[..]).map_or(true, |_| true);
-    }
-
-    #[test]
-    fn test_nocrash_register_second_message(bytes in vec(any::<u8>(), 0..200)) {
-        RegisterSecondMessage::<RistrettoPoint>::try_from(&bytes[..]).map_or(true, |_| true);
-    }
-
-    #[test]
-    fn test_nocrash_register_third_message(bytes in vec(any::<u8>(), 0..200)) {
-        RegisterThirdMessage::<crate::keypair::X25519KeyPair, sha2::Sha512>::try_from(&bytes[..]).map_or(true, |_| true);
-    }
-
-    #[test]
-    fn test_nocrash_login_first_message(bytes in vec(any::<u8>(), 0..500)) {
-        LoginFirstMessage::<Default>::try_from(&bytes[..]).map_or(true, |_| true);
-    }
-
-    #[test]
-    fn test_nocrash_login_second_message(bytes in vec(any::<u8>(), 0..500)) {
-        LoginSecondMessage::<RistrettoPoint, crate::keypair::X25519KeyPair, TripleDH, sha2::Sha512>::try_from(&bytes[..]).map_or(true, |_| true);
-    }
-
-    #[test]
-    fn test_nocrash_login_third_message(bytes in vec(any::<u8>(), 0..500)) {
-        LoginThirdMessage::<Default>::try_from(&bytes[..]).map_or(true, |_| true);
-    }
-
-    #[test]
-    fn test_nocrash_client_registration(bytes in vec(any::<u8>(), 0..700)) {
-        ClientRegistration::<Default>::try_from(&bytes[..]).map_or(true, |_| true);
-    }
-
-    #[test]
-    fn test_nocrash_server_registration(bytes in vec(any::<u8>(), 0..700)) {
-        ServerRegistration::<Default>::try_from(&bytes[..]).map_or(true, |_| true);
-    }
-
-    #[test]
-    fn test_nocrash_client_login(bytes in vec(any::<u8>(), 0..700)) {
-        ClientLogin::<Default>::try_from(&bytes[..]).map_or(true, |_| true);
-    }
-
-    #[test]
-    fn test_nocrash_server_login(bytes in vec(any::<u8>(), 0..700)) {
-        ServerLogin::<Default>::try_from(&bytes[..]).map_or(true, |_| true);
-    }
-
-}

src/tests/voprf_test_vectors.rs

@@ -0,0 +1,124 @@
+// Copyright (c) Facebook, Inc. and its affiliates.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+use crate::tests::mock_rng::CycleRng;
+use crate::{errors::*, group::Group, oprf};
+use curve25519_dalek::ristretto::RistrettoPoint;
+use generic_array::GenericArray;
+use serde_json::Value;
+use sha2::Sha512;
+
+struct VOPRFTestVectorParameters {
+    sksm: Vec<u8>,
+    input: Vec<u8>,
+    blind: Vec<u8>,
+    blinded_element: Vec<u8>,
+    evaluation_element: Vec<u8>,
+    output: Vec<u8>,
+}
+
+// Taken from https://github.com/cfrg/draft-irtf-cfrg-voprf/blob/master/draft-irtf-cfrg-voprf.md
+// in base mode
+static OPRF_RISTRETTO255_SHA512: &'static [&str] = &[
+    r#"
+    {
+        "sksm": "758cbac0e1eb4265d80f6e6489d9a74d788f7ddeda67d7fb3c08b08f44bda30a",
+        "input": "00",
+        "blind": "c604c785ada70d77a5256ae21767de8c3304115237d262134f5e46e512cf8e03",
+        "blinded_element": "3c7f2d901c0d4f245503a186086fbdf5d8b4408432b25c5163e8b5a19c258348",
+        "evaluation_element": "fc6c2b854553bf1ed6674072ed0bde1a9911e02b4bd64aa02cfb428f30251e77",
+        "output": "d8ed12382086c74564ae19b7a2b5ed9bdc52656d1fc151faaae51aaba86291e8df0b2143a92f24d44d5efd0892e2e26721d27d88745343493634a66d3a925e3a"
+    }
+    "#,
+    r#"
+    {
+        "sksm": "758cbac0e1eb4265d80f6e6489d9a74d788f7ddeda67d7fb3c08b08f44bda30a",
+        "input": "5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a",
+        "blind": "5ed895206bfc53316d307b23e46ecc6623afb3086da74189a416012be037e50b",
+        "blinded_element": "28a5e797b710f76d20a52507145fbf320a574ec2c8ab0e33e65dd2c277d0ee56",
+        "evaluation_element": "345e140b707257ae83d4911f7ead3177891e7a62c54097732802c4c7a98ab25a",
+        "output": "4d5f4221b5ebfd4d1a9dd54830e1ed0bce5a8f30a792723a6fddfe6cfe9f86bb1d95a3725818aeb725eb0b1b52e01ee9a72f47042372ef66c307770054d674fc"
+    }
+    "#,
+];
+
+fn decode(values: &Value, key: &str) -> Option<Vec<u8>> {
+    values[key]
+        .as_str()
+        .and_then(|s| hex::decode(&s.to_string()).ok())
+}
+
+fn populate_test_vectors(values: &Value) -> VOPRFTestVectorParameters {
+    VOPRFTestVectorParameters {
+        sksm: decode(&values, "sksm").unwrap(),
+        input: decode(&values, "input").unwrap(),
+        blind: decode(&values, "blind").unwrap(),
+        blinded_element: decode(&values, "blinded_element").unwrap(),
+        evaluation_element: decode(&values, "evaluation_element").unwrap(),
+        output: decode(&values, "output").unwrap(),
+    }
+}
+
+// Tests input -> blind, blinded_element
+#[test]
+fn test_blind() -> Result<(), PakeError> {
+    for tv in OPRF_RISTRETTO255_SHA512 {
+        let parameters = populate_test_vectors(&serde_json::from_str(tv).unwrap());
+        let mut rng = CycleRng::new(parameters.blind.to_vec());
+
+        let (token, blinded_element) =
+            oprf::blind::<_, RistrettoPoint, Sha512>(&parameters.input, &mut rng)?;
+
+        assert_eq!(
+            &parameters.blind,
+            &RistrettoPoint::scalar_as_bytes(&token.blind).to_vec()
+        );
+        assert_eq!(
+            &parameters.blinded_element,
+            &blinded_element.to_arr().to_vec()
+        );
+    }
+    Ok(())
+}
+
+// Tests sksm, blinded_element -> evaluation_element
+#[test]
+fn test_evaluate() -> Result<(), PakeError> {
+    for tv in OPRF_RISTRETTO255_SHA512 {
+        let parameters = populate_test_vectors(&serde_json::from_str(tv).unwrap());
+        let evaluation_element = oprf::evaluate::<RistrettoPoint>(
+            RistrettoPoint::from_element_slice(GenericArray::from_slice(
+                &parameters.blinded_element,
+            ))
+            .unwrap(),
+            &RistrettoPoint::from_scalar_slice(GenericArray::from_slice(&parameters.sksm)).unwrap(),
+        );
+
+        assert_eq!(
+            &parameters.evaluation_element,
+            &evaluation_element.to_arr().to_vec()
+        );
+    }
+    Ok(())
+}
+
+// Tests input, blind, evaluation_element -> output
+#[test]
+fn test_finalize() -> Result<(), PakeError> {
+    for tv in OPRF_RISTRETTO255_SHA512 {
+        let parameters = populate_test_vectors(&serde_json::from_str(tv).unwrap());
+
+        let output = oprf::finalize::<RistrettoPoint, Sha512>(
+            &parameters.input,
+            &RistrettoPoint::from_scalar_slice(GenericArray::from_slice(&parameters.blind))?,
+            RistrettoPoint::from_element_slice(GenericArray::from_slice(
+                &parameters.evaluation_element,
+            ))?,
+        );
+
+        assert_eq!(&parameters.output, &output.to_vec());
+    }
+    Ok(())
+}