mls_rs_crypto_traits/
dh.rs

1// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
2// Copyright by contributors to this project.
3// SPDX-License-Identifier: (Apache-2.0 OR MIT)
4
5use mls_rs_core::{
6    crypto::{HpkePublicKey, HpkeSecretKey},
7    error::IntoAnyError,
8};
9
10use alloc::vec::Vec;
11
12#[cfg(feature = "mock")]
13use mockall::automock;
14
15#[derive(Clone, Debug, Copy)]
16pub enum SamplingMethod {
17    HpkeWithBitmask(u8),
18    HpkeWithoutBitmask,
19    Raw,
20}
21
22/// A trait that provides the required DH functions, as in RFC 9180,Section 4.1
23#[cfg_attr(not(mls_build_async), maybe_async::must_be_sync)]
24#[cfg_attr(all(target_arch = "wasm32", mls_build_async), maybe_async::must_be_async(?Send))]
25#[cfg_attr(
26    all(not(target_arch = "wasm32"), mls_build_async),
27    maybe_async::must_be_async
28)]
29#[cfg_attr(feature = "mock", automock(type Error = crate::mock::TestError;))]
30pub trait DhType: Send + Sync {
31    type Error: IntoAnyError + Send + Sync;
32
33    async fn dh(
34        &self,
35        secret_key: &HpkeSecretKey,
36        public_key: &HpkePublicKey,
37    ) -> Result<Vec<u8>, Self::Error>;
38
39    /// Generate a fresh key pair. This is the only place where randomness is used in this
40    /// module. The function could be implemented in the same way as `derive` with random
41    /// `ikm`, but it could also be implemented directly with a crypto provider like OpenSSL.
42    async fn generate(&self) -> Result<(HpkeSecretKey, HpkePublicKey), Self::Error>;
43
44    /// Outputs the public key corresponding to the given secret key bytes. If the secret
45    /// key is malformed, the function should return an error.
46    async fn to_public(&self, secret_key: &HpkeSecretKey) -> Result<HpkePublicKey, Self::Error>;
47
48    /// If the output is `Some(bitmask)`, then the `Kem::derive` function will generate
49    /// the secret key by rejection sampling over random byte sequences with `bitmask`
50    /// applied to the most significant byte.
51    ///
52    /// Typical outputs for ECDH are:
53    /// * `None` for curves 25519 and X448 (no rejection sampling is needed),
54    /// * `Some(0x01)` for curve P-521 (all bits  of the first byte except the least
55    ///   significant one are filtered out),
56    /// * `Some(0xFF)`for curves P-256 and P-384 (rejection sampling is needed but no
57    ///   bits need to be filtered).
58    fn bitmask_for_rejection_sampling(&self) -> SamplingMethod;
59
60    fn secret_key_size(&self) -> usize;
61    fn public_key_size(&self) -> usize;
62
63    fn public_key_validate(&self, key: &HpkePublicKey) -> Result<(), Self::Error>;
64}
mls_rs_crypto_traits/dh.rs

mls_rs_crypto_traits/
dh.rs
