General improvements (#250)

* Remove unnecessary constraints on hash

* Remove unnecessary `Result` on `KeyPair::generate_random`

* Fix de-serialization issue on `Ke1State`

* Fix rustfmt

* Remove allocations in `envelope`

* Run Clippy for tests and rustdoc lints too

* Fix `Debug` implementation

* Fix missing constraints on `ClientRegistration`

* Fix de-serialization

* Pin temporary dependency

* Update dependencies

* Replace macro with derive-where

* Remove unnecessary installation of Rust components

* Improve macro naming

* Implement `Copy`, `Debug`, `Ord` and `PartialOrd` for high-level items

* Add `rust-version` field to `Cargo.toml`

* Remove unnecessary allocations

* Fix MSRV

* Fix no_std

* Remove unnecessary allocations

* Remove unnecessary allocations

* Not importing items from voprf helps readability

* Fix rustdoc

* Remove unnecessary allocations

* Remove unnecessary allocations

* Replace `Vec` from `diffie_hellman` with `GenericArray`

* Remove unnecessary allocations

* Remove unnecessary allocations

* Remove `cfg(feature = bench)` guard for `missing_docs`

* Fix documentation

* Remove all remaining allocations from `KeyExchange`

* Improve type-safety

* Remove all remaining allocations in `keypair`

* Remove last remaining allocations except `NonVerifiableClient` input

* Remove base64 encoding in Serde implementation

* Remove unnecessary Serde `alloc` feature

* Make curve25519-dalek optional

* Rename `serialize` crate feature to `serde`

* Switch `KeGroup` implementations to higher-level libraries

- Fixes missing clamping in X25519
- X25519 is now a separate crate feature

* Fix typo

Cargo.toml

@@ -10,22 +10,33 @@ license = "Apache-2.0 OR MIT"
 edition = "2018"
 readme = "README.md"
 resolver = "2"
+rust-version = "1.51"
 
 [features]
-default = ["u64_backend", "serialize"]
+default = ["ristretto255_u64", "serde"]
 slow-hash = ["argon2"]
 p256 = ["p256_", "voprf/p256"]
-bench = []
-u64_backend = ["curve25519-dalek/u64_backend", "voprf/ristretto255_u64"]
-u32_backend = ["curve25519-dalek/u32_backend", "voprf/ristretto255_u32"]
-std = ["curve25519-dalek/std", "getrandom", "rand/std", "rand/std_rng", "voprf/std"]
-serialize = ["serde", "base64", "generic-array/serde", "curve25519-dalek/serde", "voprf/serde"]
+ristretto255 = []
+ristretto255_u64 = ["curve25519-dalek/u64_backend", "ristretto255", "voprf/ristretto255_u64"]
+ristretto255_u32 = ["curve25519-dalek/u32_backend", "ristretto255", "voprf/ristretto255_u32"]
+ristretto255_fiat_u64 = ["curve25519-dalek/fiat_u64_backend", "ristretto255", "voprf/ristretto255_fiat_u64"]
+ristretto255_fiat_u32 = ["curve25519-dalek/fiat_u32_backend", "ristretto255", "voprf/ristretto255_fiat_u32"]
+ristretto255_simd = ["curve25519-dalek/simd_backend", "ristretto255", "voprf/ristretto255_simd"]
+x25519 = []
+x25519_u64 = ["x25519", "x25519-dalek/u64_backend"]
+x25519_u32 = ["x25519", "x25519-dalek/u32_backend"]
+x25519_fiat_u64 = ["x25519", "x25519-dalek/fiat_u64_backend"]
+x25519_fiat_u32 = ["x25519", "x25519-dalek/fiat_u32_backend"]
+# x25519-dalek isn't properly re-exposing `simd_backend`.
+x25519_simd = ["curve25519-dalek/simd_backend", "x25519", "x25519-dalek/nightly"]
+std = ["getrandom", "rand/std", "rand/std_rng", "voprf/std"]
+serde = ["serde_", "generic-array/serde", "voprf/serde"]
 
 [dependencies]
 argon2 = { version = "0.3", default-features = false, features = ["alloc"], optional = true }
-base64 = { version = "0.13", default-features = false, features = ["alloc"], optional = true }
 constant_time_eq = "0.1"
-curve25519-dalek = { version = "3", default-features = false }
+curve25519-dalek = { version = "3", default-features = false, optional = true }
+derive-where = { version = "1.0.0-rc.1", features = ["zeroize"] }
 digest = "0.9"
 displaydoc = { version = "0.2", default-features = false }
 generic-array = "0.14"
@@ -34,9 +45,10 @@ hkdf = "0.11"
 hmac = "0.11"
 p256_ = { package = "p256", version = "0.9", default-features = false, features = ["arithmetic", "zeroize"], optional = true }
 rand = { version = "0.8", default-features = false }
-serde = { version = "1", default-features = false, features = ["alloc", "derive"], optional = true }
+serde_ = { version = "1", package = "serde", default-features = false, features = ["derive"], optional = true }
 subtle = { version = "2.3", default-features = false }
-voprf = { version = "0.2", default-features = false, features = ["danger"] }
+voprf = { git = "https://github.com/khonsulabs/voprf", rev = "f8c19eab4ecc9e7a2a5ae26c59661ce797229566", default-features = false, features = ["danger"] }
+x25519-dalek = { version = "1", default-features = false, optional = true }
 zeroize = { version = "1", features = ["zeroize_derive"] }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
@@ -45,7 +57,7 @@ getrandom = { version = "0.2", features = ["js"], optional = true }
 [dev-dependencies]
 base64 = "0.13"
 bincode = "1"
-chacha20poly1305 = "0.8"
+chacha20poly1305 = "0.9"
 criterion = "0.3"
 hex = "0.4"
 json = "0.12"
@@ -55,9 +67,9 @@ serde_json = "1"
 sha2 = "0.9"
 proptest = "1"
 regex = "1"
-rustyline = "8"
+# Version 9.1 requires an MSRV of 1.56
+rustyline = "~9.0"
 
 [[bench]]
 name = "opaque"
 harness = false
-required-features = ["bench"]