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// 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_crypto_traits::KdfType;
use alloc::vec::Vec;
use core::fmt::{self, Debug};
#[derive(Clone, Eq, PartialEq)]
pub(crate) struct HpkeKdf<K: KdfType> {
suite_id: Vec<u8>,
kdf: K,
}
impl<K: KdfType + Debug> Debug for HpkeKdf<K> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("HpkeKdf")
.field(
"suite_id",
&mls_rs_core::debug::pretty_bytes(&self.suite_id),
)
.field("kdf", &self.kdf)
.finish()
}
}
impl<K: KdfType> HpkeKdf<K> {
pub fn new(suite_id: Vec<u8>, kdf: K) -> Self {
Self { suite_id, kdf }
}
pub fn extract_size(&self) -> usize {
self.kdf.extract_size()
}
/* draft-irtf-cfrg-hpke-09 section 4 Cryptographic Dependencies */
#[cfg_attr(not(mls_build_async), maybe_async::must_be_sync)]
pub async fn labeled_extract(
&self,
salt: &[u8],
label: &[u8],
ikm: &[u8],
) -> Result<Vec<u8>, <K as KdfType>::Error> {
self.kdf
.extract(
salt,
&[b"HPKE-v1" as &[u8], &self.suite_id, label, ikm].concat(),
)
.await
}
/* draft-irtf-cfrg-hpke-09 section 4 Cryptographic Dependencies */
#[cfg_attr(not(mls_build_async), maybe_async::must_be_sync)]
pub async fn labeled_expand(
&self,
key: &[u8],
label: &[u8],
info: &[u8],
len: usize,
) -> Result<Vec<u8>, <K as KdfType>::Error> {
let labeled_info = [
&(len as u16).to_be_bytes() as &[u8],
b"HPKE-v1",
&self.suite_id,
label,
info,
]
.concat();
self.kdf.expand(key, &labeled_info, len).await
}
/* draft-irtf-cfrg-hpke-09 section 4.1 DH-Based KEM */
#[cfg_attr(not(mls_build_async), maybe_async::must_be_sync)]
pub async fn labeled_extract_then_expand(
&self,
ikm: &[u8],
ctx: &[u8],
len: usize,
) -> Result<Vec<u8>, <K as KdfType>::Error> {
let eae_prk = self.labeled_extract(&[], b"eae_prk", ikm).await?;
self.labeled_expand(&eae_prk, b"shared_secret", ctx, len)
.await
}
}