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use alloc::vec::Vec;
use mls_rs_core::mls_rs_codec::{MlsDecode, MlsEncode};
use crate::kem_combiner::ghp::{ByteVecCodec, ByteVecEncoder};
use crate::kem_combiner::Error;
#[derive(Debug, Clone)]
pub struct MlsByteVecCodec;
impl<const N: usize> ByteVecEncoder<N> for MlsByteVecCodec {
type Error = Error;
fn encode(&self, data: [&[u8]; N]) -> Result<Vec<u8>, Error> {
data.mls_encode_to_vec().map_err(Error::MlsCodecError)
}
}
impl<const N: usize> ByteVecCodec<N> for MlsByteVecCodec {
fn decode(&self, data: &[u8]) -> Result<[Vec<u8>; N], Error> {
let vecs = Vec::<Vec<u8>>::mls_decode(&mut &*data).map_err(Error::MlsCodecError)?;
vecs.try_into()
.map_err(|vecs: Vec<Vec<u8>>| Error::InvalidInputLength(vecs.len()))
}
}
/// The concatenation codec for two chunks to instantiate [GhpKemCombiner] as specified in the
/// with input KEM's whose ciphertexts and public / secret keys are of fixed size.
#[derive(Debug, Clone)]
pub struct CatCodec2 {
pub chunk_lengths: [usize; 2],
}
/// The concatenation codec for seven chunks to instantiate [GhpKemCombiner] as specified in the
/// with input KEM's whose ciphertexts and public / secret keys are of fixed size.
#[derive(Debug, Clone)]
pub struct CatCodec7 {
pub chunk_lengths: [usize; 7],
}
impl ByteVecEncoder<2> for CatCodec2 {
type Error = Error;
fn encode(&self, data: [&[u8]; 2]) -> Result<Vec<u8>, Error> {
Ok(data.concat())
}
}
impl ByteVecCodec<2> for CatCodec2 {
fn decode(&self, data: &[u8]) -> Result<[Vec<u8>; 2], Error> {
if data.len() != self.chunk_lengths.iter().sum::<usize>() {
return Err(Error::InvalidKeyData);
}
let (first, second) = data.split_at(self.chunk_lengths[0]);
Ok([first.to_vec(), second.to_vec()])
}
}
impl ByteVecEncoder<7> for CatCodec7 {
type Error = Error;
fn encode(&self, data: [&[u8]; 7]) -> Result<Vec<u8>, Error> {
Ok(data.concat())
}
}
#[cfg(test)]
mod tests {
use crate::kem_combiner::{
byte_vec_codecs::{CatCodec2, CatCodec7, MlsByteVecCodec},
ghp::{ByteVecCodec, ByteVecEncoder},
};
#[test]
fn mls_byte_vec_codec() {
let data = [b"hello".as_slice(), b"world"];
let encoded = MlsByteVecCodec.encode(data).unwrap();
let [decoded1, decoded2] = MlsByteVecCodec.decode(&encoded).unwrap();
assert_eq!(data, [decoded1, decoded2]);
}
#[test]
fn cat_codec_2() {
let data = [b"hello".as_slice(), b"world!"];
let codec = CatCodec2 {
chunk_lengths: [5, 6],
};
let encoded = codec.encode(data).unwrap();
let [decoded1, decoded2] = codec.decode(&encoded).unwrap();
assert_eq!(data, [decoded1, decoded2]);
}
#[test]
fn cat_codec_7() {
let data = [
b"1".as_slice(),
b"12",
b"123",
b"1234",
b"12345",
b"123456",
b"1234567",
];
let codec = CatCodec7 {
chunk_lengths: [1, 2, 3, 4, 5, 6, 7],
};
let encoded = codec.encode(data).unwrap();
assert_eq!(encoded, b"1121231234123451234561234567");
}
}