Revision control
Copy as Markdown
Other Tools
// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// Copyright by contributors to this project.
// SPDX-License-Identifier: (Apache-2.0 OR MIT)
use mls_rs_core::{
crypto::{CipherSuite, HpkePublicKey, HpkeSecretKey},
error::IntoAnyError,
};
use alloc::vec::Vec;
#[cfg(feature = "mock")]
use mockall::automock;
/// A trait that provides the required KEM functions
#[cfg_attr(not(mls_build_async), maybe_async::must_be_sync)]
#[cfg_attr(all(target_arch = "wasm32", mls_build_async), maybe_async::must_be_async(?Send))]
#[cfg_attr(
all(not(target_arch = "wasm32"), mls_build_async),
maybe_async::must_be_async
)]
#[cfg_attr(feature = "mock", automock(type Error = crate::mock::TestError;))]
pub trait KemType: Send + Sync {
type Error: IntoAnyError + Send + Sync;
/// KEM Id, as specified in RFC 9180, Section 5.1 and Table 2.
fn kem_id(&self) -> u16;
async fn derive(&self, ikm: &[u8]) -> Result<(HpkeSecretKey, HpkePublicKey), Self::Error>;
async fn generate(&self) -> Result<(HpkeSecretKey, HpkePublicKey), Self::Error>;
fn public_key_validate(&self, key: &HpkePublicKey) -> Result<(), Self::Error>;
async fn encap(&self, remote_key: &HpkePublicKey) -> Result<KemResult, Self::Error>;
async fn decap(
&self,
enc: &[u8],
secret_key: &HpkeSecretKey,
local_public: &HpkePublicKey,
) -> Result<Vec<u8>, Self::Error>;
}
/// Struct to represent the output of the kem [encap](KemType::encap) function
pub struct KemResult {
pub shared_secret: Vec<u8>,
pub enc: Vec<u8>,
}
impl KemResult {
pub fn new(shared_secret: Vec<u8>, enc: Vec<u8>) -> Self {
Self { shared_secret, enc }
}
pub fn shared_secret(&self) -> &[u8] {
&self.shared_secret
}
/// Returns the ciphertext encapsulating the shared secret.
pub fn enc(&self) -> &[u8] {
&self.enc
}
}
/// Kem identifiers for HPKE
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
#[repr(u16)]
#[non_exhaustive]
pub enum KemId {
DhKemP256Sha256 = 0x0010,
DhKemP384Sha384 = 0x0011,
DhKemP521Sha512 = 0x0012,
DhKemX25519Sha256 = 0x0020,
DhKemX448Sha512 = 0x0021,
}
impl KemId {
pub fn new(cipher_suite: CipherSuite) -> Option<Self> {
match cipher_suite {
CipherSuite::CURVE25519_AES128 | CipherSuite::CURVE25519_CHACHA => {
Some(KemId::DhKemX25519Sha256)
}
CipherSuite::P256_AES128 => Some(KemId::DhKemP256Sha256),
CipherSuite::CURVE448_AES256 | CipherSuite::CURVE448_CHACHA => {
Some(KemId::DhKemX448Sha512)
}
CipherSuite::P384_AES256 => Some(KemId::DhKemP384Sha384),
CipherSuite::P521_AES256 => Some(KemId::DhKemP521Sha512),
_ => None,
}
}
pub fn n_secret(&self) -> usize {
match self {
KemId::DhKemP256Sha256 => 32,
KemId::DhKemP384Sha384 => 48,
KemId::DhKemP521Sha512 => 64,
KemId::DhKemX25519Sha256 => 32,
KemId::DhKemX448Sha512 => 64,
}
}
}