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use crate::{
aead::{aes, chacha},
cpu, error, hkdf,
};
use core::convert::{TryFrom, TryInto};
pub struct HeaderProtectionKey {
inner: KeyInner,
algorithm: &'static Algorithm,
}
#[allow(clippy::large_enum_variant, variant_size_differences)]
enum KeyInner {
Aes(aes::Key),
ChaCha20(chacha::Key),
}
impl From<hkdf::Okm<'_, &'static Algorithm>> for HeaderProtectionKey {
fn from(okm: hkdf::Okm<&'static Algorithm>) -> Self {
let mut key_bytes = [0; super::MAX_KEY_LEN];
let algorithm = *okm.len();
let key_bytes = &mut key_bytes[..algorithm.key_len()];
okm.fill(key_bytes).unwrap();
Self::new(algorithm, key_bytes).unwrap()
}
}
impl HeaderProtectionKey {
pub fn new(
algorithm: &'static Algorithm,
key_bytes: &[u8],
) -> Result<Self, error::Unspecified> {
Ok(Self {
inner: (algorithm.init)(key_bytes, cpu::features())?,
algorithm,
})
}
pub fn new_mask(&self, sample: &[u8]) -> Result<[u8; 5], error::Unspecified> {
let sample = <&[u8; SAMPLE_LEN]>::try_from(sample)?;
let out = (self.algorithm.new_mask)(&self.inner, *sample);
Ok(out)
}
#[inline(always)]
pub fn algorithm(&self) -> &'static Algorithm {
self.algorithm
}
}
const SAMPLE_LEN: usize = super::TAG_LEN;
pub type Sample = [u8; SAMPLE_LEN];
pub struct Algorithm {
init: fn(key: &[u8], cpu_features: cpu::Features) -> Result<KeyInner, error::Unspecified>,
new_mask: fn(key: &KeyInner, sample: Sample) -> [u8; 5],
key_len: usize,
id: AlgorithmID,
}
impl hkdf::KeyType for &'static Algorithm {
#[inline]
fn len(&self) -> usize {
self.key_len()
}
}
impl Algorithm {
#[inline(always)]
pub fn key_len(&self) -> usize {
self.key_len
}
#[inline(always)]
pub fn sample_len(&self) -> usize {
SAMPLE_LEN
}
}
derive_debug_via_id!(Algorithm);
#[derive(Debug, Eq, PartialEq)]
enum AlgorithmID {
AES_128,
AES_256,
CHACHA20,
}
impl PartialEq for Algorithm {
fn eq(&self, other: &Self) -> bool {
self.id == other.id
}
}
impl Eq for Algorithm {}
pub static AES_128: Algorithm = Algorithm {
key_len: 16,
init: aes_init_128,
new_mask: aes_new_mask,
id: AlgorithmID::AES_128,
};
pub static AES_256: Algorithm = Algorithm {
key_len: 32,
init: aes_init_256,
new_mask: aes_new_mask,
id: AlgorithmID::AES_256,
};
fn aes_init_128(key: &[u8], cpu_features: cpu::Features) -> Result<KeyInner, error::Unspecified> {
let aes_key = aes::Key::new(key, aes::Variant::AES_128, cpu_features)?;
Ok(KeyInner::Aes(aes_key))
}
fn aes_init_256(key: &[u8], cpu_features: cpu::Features) -> Result<KeyInner, error::Unspecified> {
let aes_key = aes::Key::new(key, aes::Variant::AES_256, cpu_features)?;
Ok(KeyInner::Aes(aes_key))
}
fn aes_new_mask(key: &KeyInner, sample: Sample) -> [u8; 5] {
let aes_key = match key {
KeyInner::Aes(key) => key,
_ => unreachable!(),
};
aes_key.new_mask(sample)
}
pub static CHACHA20: Algorithm = Algorithm {
key_len: chacha::KEY_LEN,
init: chacha20_init,
new_mask: chacha20_new_mask,
id: AlgorithmID::CHACHA20,
};
fn chacha20_init(key: &[u8], _todo: cpu::Features) -> Result<KeyInner, error::Unspecified> {
let chacha20_key: [u8; chacha::KEY_LEN] = key.try_into()?;
Ok(KeyInner::ChaCha20(chacha::Key::from(chacha20_key)))
}
fn chacha20_new_mask(key: &KeyInner, sample: Sample) -> [u8; 5] {
let chacha20_key = match key {
KeyInner::ChaCha20(key) => key,
_ => unreachable!(),
};
chacha20_key.new_mask(sample)
}