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Adding a hash type to CipherSuite (#24)

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This commit is contained in:
Kevin Lewi
2020-07-27 15:25:04 -07:00
committed by GitHub
parent 72a3928cbb
commit c2edb2d95e
15 changed files with 570 additions and 492 deletions
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src/key_exchange/traits.rs
+2 -1
View File
@@ -5,13 +5,14 @@
use crate::{
errors::{InternalPakeError, ProtocolError},
hash::Hash,
keypair::{Key, KeyPair},
};
use rand_core::{CryptoRng, RngCore};
use std::convert::TryFrom;
pub trait KeyExchange {
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;
src/key_exchange/tripledh.rs
+24 -23
View File
@@ -6,10 +6,12 @@
//! An implementation of the Triple Diffie-Hellman key exchange protocol
use crate::{
errors::{utils::check_slice_size, InternalPakeError, PakeError, ProtocolError},
hash::Hash,
key_exchange::traits::{KeyExchange, ToBytes},
keypair::{Key, KeyPair, SizedBytes},
sized_bytes_using_constant_and_try_from,
};
use digest::Digest;
use generic_array::{
typenum::{U64, U96},
GenericArray,
@@ -18,7 +20,6 @@ use hkdf::Hkdf;
use hmac::{Hmac, Mac, NewMac};
use rand_core::{CryptoRng, RngCore};
use sha2::{Digest, Sha256};
use std::convert::TryFrom;
const KEY_LEN: usize = 32;
@@ -29,9 +30,9 @@ const KE2_MESSAGE_LEN: usize = NONCE_LEN + 2 * KEY_LEN;
static STR_3DH: &[u8] = b"3DH keys";
/// The Triple Diffie-Hellman key exchange implementation
pub struct TripleDH {}
pub struct TripleDH;
impl KeyExchange for TripleDH {
impl<D: Hash> KeyExchange<D> for TripleDH {
type KE1State = KE1State;
type KE2State = KE2State;
type KE1Message = KE1Message;
@@ -52,7 +53,7 @@ impl KeyExchange for TripleDH {
};
let l1_data: Vec<u8> = [&l1_component[..], &ke1_message.to_bytes()].concat();
let mut hasher = Sha256::new();
let mut hasher = D::new();
hasher.update(&l1_data);
let hashed_l1 = hasher.finalize();
@@ -78,7 +79,7 @@ impl KeyExchange for TripleDH {
let mut server_nonce = [0u8; NONCE_LEN];
rng.fill_bytes(&mut server_nonce);
let (shared_secret, km2, km3) = derive_3dh_keys::<KeyFormat>(
let (shared_secret, km2, km3) = derive_3dh_keys::<KeyFormat, D>(
TripleDHComponents {
pk1: ke1_message.client_e_pk.clone(),
sk1: server_e_kp.private().clone(),
@@ -93,7 +94,7 @@ impl KeyExchange for TripleDH {
KeyFormat::public_from_private(&server_s_sk),
)?;
let mut hasher = Sha256::new();
let mut hasher = D::new();
hasher.update(&l1_bytes);
let hashed_l1 = hasher.finalize();
@@ -105,11 +106,11 @@ impl KeyExchange for TripleDH {
]
.concat();
let mut hasher2 = Sha256::new();
let mut hasher2 = D::new();
hasher2.update(&transcript2);
let hashed_transcript = hasher2.finalize();
let mut mac = Hmac::<Sha256>::new_varkey(&km2).map_err(|_| InternalPakeError::HmacError)?;
let mut mac = Hmac::<D>::new_varkey(&km2).map_err(|_| InternalPakeError::HmacError)?;
mac.update(&hashed_transcript);
Ok((
@@ -133,7 +134,7 @@ impl KeyExchange for TripleDH {
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>(
let (shared_secret, km2, km3) = derive_3dh_keys::<KeyFormat, D>(
TripleDHComponents {
pk1: ke2_message.server_e_pk.clone(),
sk1: ke1_state.client_e_sk.clone(),
@@ -156,12 +157,12 @@ impl KeyExchange for TripleDH {
]
.concat();
let mut hasher = Sha256::new();
let mut hasher = D::new();
hasher.update(&transcript);
let hashed_transcript = hasher.finalize();
let mut server_mac =
Hmac::<Sha256>::new_varkey(&km2).map_err(|_| InternalPakeError::HmacError)?;
Hmac::<D>::new_varkey(&km2).map_err(|_| InternalPakeError::HmacError)?;
server_mac.update(&hashed_transcript);
if ke2_message.mac != server_mac.finalize().into_bytes().to_vec() {
@@ -171,7 +172,7 @@ impl KeyExchange for TripleDH {
}
let mut client_mac =
Hmac::<Sha256>::new_varkey(&km3).map_err(|_| InternalPakeError::HmacError)?;
Hmac::<D>::new_varkey(&km3).map_err(|_| InternalPakeError::HmacError)?;
client_mac.update(&hashed_transcript);
Ok((
@@ -187,7 +188,7 @@ impl KeyExchange for TripleDH {
ke2_state: &Self::KE2State,
) -> Result<Vec<u8>, ProtocolError> {
let mut client_mac =
Hmac::<Sha256>::new_varkey(&ke2_state.km3).map_err(|_| InternalPakeError::HmacError)?;
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() {
@@ -350,21 +351,21 @@ struct TripleDHComponents {
}
// Consists of a shared secret, followed by two mac keys
type TripleDHDerivationResult = (
GenericArray<u8, <Sha256 as Digest>::OutputSize>,
GenericArray<u8, <Sha256 as Digest>::OutputSize>,
GenericArray<u8, <Sha256 as Digest>::OutputSize>,
type TripleDHDerivationResult<D> = (
GenericArray<u8, <D as Hash>::OutputSize>,
GenericArray<u8, <D as Hash>::OutputSize>,
GenericArray<u8, <D as Hash>::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>>(
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, ProtocolError> {
) -> Result<TripleDHDerivationResult<D>, ProtocolError> {
let ikm: Vec<u8> = [
&KeyFormat::diffie_hellman(dh.pk1, dh.sk1)[..],
&KeyFormat::diffie_hellman(dh.pk2, dh.sk2)[..],
@@ -383,13 +384,13 @@ fn derive_3dh_keys<KeyFormat: KeyPair<Repr = Key>>(
const OUTPUT_SIZE: usize = 32;
let mut okm = [0u8; 3 * OUTPUT_SIZE];
let h = Hkdf::<Sha256>::new(None, &ikm);
let h = Hkdf::<D>::new(None, &ikm);
h.expand(&info, &mut okm)
.map_err(|_| InternalPakeError::HkdfError)?;
Ok((
*GenericArray::from_slice(&okm[..OUTPUT_SIZE]),
*GenericArray::from_slice(&okm[OUTPUT_SIZE..2 * OUTPUT_SIZE]),
*GenericArray::from_slice(&okm[2 * OUTPUT_SIZE..]),
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..]),
))
}