use super::aead;
use alloc::boxed::Box;
use alloc::format;
use openssl::symm::{encrypt, Cipher};
use rustls::{
crypto::cipher::{AeadKey, Iv},
quic, Error,
};
pub(crate) struct KeyBuilder {
pub(crate) packet_algo: aead::Algorithm,
pub(crate) header_algo: HeaderProtectionAlgorithm,
pub(crate) confidentiality_limit: u64,
pub(crate) integrity_limit: u64,
}
struct PacketKey {
crypter: aead::MessageCrypter,
confidentiality_limit: u64,
integrity_limit: u64,
}
#[derive(Debug, Clone, Copy)]
pub(crate) enum HeaderProtectionAlgorithm {
Aes128,
Aes256,
#[cfg(feature = "chacha")]
ChaCha20,
}
pub(crate) struct HeaderProtectionKey {
algo: HeaderProtectionAlgorithm,
key: AeadKey,
}
const SAMPLE_LEN: usize = 16;
impl quic::Algorithm for KeyBuilder {
fn packet_key(&self, key: AeadKey, iv: Iv) -> Box<dyn quic::PacketKey> {
let crypter = aead::MessageCrypter {
algo: self.packet_algo,
key,
iv,
};
Box::new(PacketKey {
crypter,
confidentiality_limit: self.confidentiality_limit,
integrity_limit: self.integrity_limit,
})
}
fn header_protection_key(&self, key: AeadKey) -> Box<dyn quic::HeaderProtectionKey> {
Box::new(HeaderProtectionKey {
algo: self.header_algo,
key,
})
}
fn aead_key_len(&self) -> usize {
self.packet_algo.openssl_cipher().key_length()
}
}
impl quic::PacketKey for PacketKey {
fn encrypt_in_place(
&self,
packet_number: u64,
header: &[u8],
payload: &mut [u8],
) -> Result<quic::Tag, Error> {
let tag = self
.crypter
.encrypt_in_place(packet_number, header, payload)?;
Ok(quic::Tag::from(tag.as_ref()))
}
fn decrypt_in_place<'a>(
&self,
packet_number: u64,
header: &[u8],
payload: &'a mut [u8],
) -> Result<&'a [u8], Error> {
let plaintext_len = self
.crypter
.decrypt_in_place(packet_number, header, payload)?;
Ok(&payload[..plaintext_len])
}
fn tag_len(&self) -> usize {
aead::TAG_LEN
}
fn confidentiality_limit(&self) -> u64 {
self.confidentiality_limit
}
fn integrity_limit(&self) -> u64 {
self.integrity_limit
}
}
impl quic::HeaderProtectionKey for HeaderProtectionKey {
fn encrypt_in_place(
&self,
sample: &[u8],
first: &mut u8,
packet_number: &mut [u8],
) -> Result<(), Error> {
let mask = self.mask(sample)?;
let (first_mask, packet_number_mask) = mask.split_first().expect("mask is 5 bytes long");
if packet_number_mask.len() < packet_number.len() {
return Err(Error::General("packet number exceeds 4 bytes".into()));
}
let packet_number_length = (*first & 0x03) + 1;
if (*first & 0x80) == 0x80 {
*first ^= first_mask & 0x0f;
} else {
*first ^= first_mask & 0x1f;
}
packet_number
.iter_mut()
.zip(packet_number_mask)
.take(packet_number_length as usize)
.for_each(|(packet_number_byte, mask)| *packet_number_byte ^= mask);
Ok(())
}
fn decrypt_in_place(
&self,
sample: &[u8],
first: &mut u8,
packet_number: &mut [u8],
) -> Result<(), Error> {
let mask = self.mask(sample)?;
let (first_mask, packet_number_mask) = mask.split_first().expect("mask is 5 bytes long");
if packet_number_mask.len() < packet_number.len() {
return Err(Error::General("packet number exceeds 4 bytes".into()));
}
if (*first & 0x80) == 0x80 {
*first ^= first_mask & 0x0f;
} else {
*first ^= first_mask & 0x1f;
}
let packet_number_length = (*first & 0x03) + 1;
packet_number
.iter_mut()
.zip(packet_number_mask)
.take(packet_number_length as usize)
.for_each(|(packet_number_byte, mask)| *packet_number_byte ^= mask);
Ok(())
}
fn sample_len(&self) -> usize {
SAMPLE_LEN
}
}
impl HeaderProtectionAlgorithm {
fn openssl_cipher(self) -> Cipher {
match self {
HeaderProtectionAlgorithm::Aes128 => Cipher::aes_128_ecb(),
HeaderProtectionAlgorithm::Aes256 => Cipher::aes_256_ecb(),
#[cfg(feature = "chacha")]
HeaderProtectionAlgorithm::ChaCha20 => Cipher::chacha20(),
}
}
}
impl HeaderProtectionKey {
fn mask(&self, sample: &[u8]) -> Result<[u8; 5], Error> {
let mut mask = [0; 5];
match self.algo {
HeaderProtectionAlgorithm::Aes128 | HeaderProtectionAlgorithm::Aes256 => {
let block = encrypt(self.algo.openssl_cipher(), self.key.as_ref(), None, sample)
.map_err(|e| Error::General(format!("OpenSSL error: {e}")))?;
mask.copy_from_slice(&block[..5]);
}
#[cfg(feature = "chacha")]
HeaderProtectionAlgorithm::ChaCha20 => {
let block = encrypt(
self.algo.openssl_cipher(),
self.key.as_ref(),
Some(sample),
&[0; 5],
)
.map_err(|e| Error::General(format!("OpenSSL error: {e}")))?;
mask.copy_from_slice(&block[..5]);
}
}
Ok(mask)
}
}
#[cfg(test)]
mod test {
use rustls::{
quic::{Keys, Version},
Side,
};
use super::super::tls13::TLS13_AES_128_GCM_SHA256_INTERNAL;
#[test]
fn initial_test_vector_v2() {
let icid = [0x83, 0x94, 0xc8, 0xf0, 0x3e, 0x51, 0x57, 0x08];
let server = Keys::initial(
Version::V2,
TLS13_AES_128_GCM_SHA256_INTERNAL,
TLS13_AES_128_GCM_SHA256_INTERNAL.quic.unwrap(),
&icid,
Side::Server,
);
let mut server_payload = [
0x02, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00, 0x40, 0x5a, 0x02, 0x00, 0x00, 0x56, 0x03,
0x03, 0xee, 0xfc, 0xe7, 0xf7, 0xb3, 0x7b, 0xa1, 0xd1, 0x63, 0x2e, 0x96, 0x67, 0x78,
0x25, 0xdd, 0xf7, 0x39, 0x88, 0xcf, 0xc7, 0x98, 0x25, 0xdf, 0x56, 0x6d, 0xc5, 0x43,
0x0b, 0x9a, 0x04, 0x5a, 0x12, 0x00, 0x13, 0x01, 0x00, 0x00, 0x2e, 0x00, 0x33, 0x00,
0x24, 0x00, 0x1d, 0x00, 0x20, 0x9d, 0x3c, 0x94, 0x0d, 0x89, 0x69, 0x0b, 0x84, 0xd0,
0x8a, 0x60, 0x99, 0x3c, 0x14, 0x4e, 0xca, 0x68, 0x4d, 0x10, 0x81, 0x28, 0x7c, 0x83,
0x4d, 0x53, 0x11, 0xbc, 0xf3, 0x2b, 0xb9, 0xda, 0x1a, 0x00, 0x2b, 0x00, 0x02, 0x03,
0x04,
];
let mut server_header = [
0xd1, 0x6b, 0x33, 0x43, 0xcf, 0x00, 0x08, 0xf0, 0x67, 0xa5, 0x50, 0x2a, 0x42, 0x62,
0xb5, 0x00, 0x40, 0x75, 0x00, 0x01,
];
let tag = server
.local
.packet
.encrypt_in_place(1, &server_header, &mut server_payload)
.unwrap();
let (first, rest) = server_header.split_at_mut(1);
let rest_len = rest.len();
server
.local
.header
.encrypt_in_place(
&server_payload[2..18],
&mut first[0],
&mut rest[rest_len - 2..],
)
.unwrap();
let mut server_packet = server_header.to_vec();
server_packet.extend(server_payload);
server_packet.extend(tag.as_ref());
let expected_server_packet = [
0xdc, 0x6b, 0x33, 0x43, 0xcf, 0x00, 0x08, 0xf0, 0x67, 0xa5, 0x50, 0x2a, 0x42, 0x62,
0xb5, 0x00, 0x40, 0x75, 0xd9, 0x2f, 0xaa, 0xf1, 0x6f, 0x05, 0xd8, 0xa4, 0x39, 0x8c,
0x47, 0x08, 0x96, 0x98, 0xba, 0xee, 0xa2, 0x6b, 0x91, 0xeb, 0x76, 0x1d, 0x9b, 0x89,
0x23, 0x7b, 0xbf, 0x87, 0x26, 0x30, 0x17, 0x91, 0x53, 0x58, 0x23, 0x00, 0x35, 0xf7,
0xfd, 0x39, 0x45, 0xd8, 0x89, 0x65, 0xcf, 0x17, 0xf9, 0xaf, 0x6e, 0x16, 0x88, 0x6c,
0x61, 0xbf, 0xc7, 0x03, 0x10, 0x6f, 0xba, 0xf3, 0xcb, 0x4c, 0xfa, 0x52, 0x38, 0x2d,
0xd1, 0x6a, 0x39, 0x3e, 0x42, 0x75, 0x75, 0x07, 0x69, 0x80, 0x75, 0xb2, 0xc9, 0x84,
0xc7, 0x07, 0xf0, 0xa0, 0x81, 0x2d, 0x8c, 0xd5, 0xa6, 0x88, 0x1e, 0xaf, 0x21, 0xce,
0xda, 0x98, 0xf4, 0xbd, 0x23, 0xf6, 0xfe, 0x1a, 0x3e, 0x2c, 0x43, 0xed, 0xd9, 0xce,
0x7c, 0xa8, 0x4b, 0xed, 0x85, 0x21, 0xe2, 0xe1, 0x40,
];
assert_eq!(server_packet[..], expected_server_packet[..]);
}
#[cfg(feature = "chacha")]
#[test]
fn test_short_packet_length() {
use rustls::crypto::cipher::AeadKey;
let sample = [
0x5e, 0x5c, 0xd5, 0x5c, 0x41, 0xf6, 0x90, 0x80, 0x57, 0x5d, 0x79, 0x99, 0xc2, 0x5a,
0x5b, 0xfb,
];
let key: [u8; 32] = [
0x25, 0xa2, 0x82, 0xb9, 0xe8, 0x2f, 0x06, 0xf2, 0x1f, 0x48, 0x89, 0x17, 0xa4, 0xfc,
0x8f, 0x1b, 0x73, 0x57, 0x36, 0x85, 0x60, 0x85, 0x97, 0xd0, 0xef, 0xcb, 0x07, 0x6b,
0x0a, 0xb7, 0xa7, 0xa4,
];
let hpk = super::HeaderProtectionKey {
algo: super::HeaderProtectionAlgorithm::ChaCha20,
key: AeadKey::from(key),
};
let mask = hpk.mask(&sample).unwrap();
assert_eq!(mask, [0xae, 0xfe, 0xfe, 0x7d, 0x03]);
}
}