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/* Copyright (C) 2021 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program under the terms of
* the GNU General Public License version 2 as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
use aes::cipher::generic_array::GenericArray;
use aes::Aes128;
use aes::BlockEncrypt;
use aes::NewBlockCipher;
use aes_gcm::AeadInPlace;
use aes_gcm::Aes128Gcm;
use aes_gcm::NewAead;
use hkdf::Hkdf;
use sha2::Sha256;
pub const AES128_KEY_LEN: usize = 16;
pub const AES128_TAG_LEN: usize = 16;
pub const AES128_IV_LEN: usize = 12;
pub struct HeaderProtectionKey(Aes128);
impl HeaderProtectionKey {
fn new(secret: &[u8], version: u32) -> Self {
let hk = Hkdf::<Sha256>::from_prk(secret).unwrap();
let mut secret = [0u8; AES128_KEY_LEN];
let quichp = if version == 0x6b3343cf {
b"quicv2 hp" as &[u8]
} else {
b"quic hp" as &[u8]
};
hkdf_expand_label(&hk, quichp, &mut secret, AES128_KEY_LEN as u16);
return Self(Aes128::new(GenericArray::from_slice(&secret)));
}
pub fn decrypt_in_place(
&self, sample: &[u8], first: &mut u8, packet_number: &mut [u8],
) -> Result<(), ()> {
let mut mask = GenericArray::clone_from_slice(sample);
self.0.encrypt_block(&mut mask);
let (first_mask, pn_mask) = mask.split_first().unwrap();
let bits = if (*first & 0x80) != 0 {
0x0f // Long header: 4 bits masked
} else {
0x1f // Short header: 5 bits masked
};
*first ^= first_mask & bits;
let pn_len = (*first & 0x03) as usize + 1;
for (dst, m) in packet_number.iter_mut().zip(pn_mask).take(pn_len) {
*dst ^= m;
}
Ok(())
}
}
pub struct PacketKey {
key: Aes128Gcm,
iv: [u8; AES128_IV_LEN],
}
impl PacketKey {
fn new(secret: &[u8], version: u32) -> Self {
let hk = Hkdf::<Sha256>::from_prk(secret).unwrap();
let mut secret = [0u8; AES128_KEY_LEN];
let quickey = if version == 0x6b3343cf {
b"quicv2 key" as &[u8]
} else {
b"quic key" as &[u8]
};
hkdf_expand_label(&hk, quickey, &mut secret, AES128_KEY_LEN as u16);
let key = Aes128Gcm::new(GenericArray::from_slice(&secret));
let mut r = PacketKey {
key,
iv: [0u8; AES128_IV_LEN],
};
let quiciv = if version == 0x6b3343cf {
b"quicv2 iv" as &[u8]
} else {
b"quic iv" as &[u8]
};
hkdf_expand_label(&hk, quiciv, &mut r.iv, AES128_IV_LEN as u16);
return r;
}
pub fn decrypt_in_place<'a>(
&self, packet_number: u64, header: &[u8], payload: &'a mut [u8],
) -> Result<&'a [u8], ()> {
if payload.len() < AES128_TAG_LEN {
return Err(());
}
let mut nonce = [0; AES128_IV_LEN];
nonce[4..].copy_from_slice(&packet_number.to_be_bytes());
for (nonce, inp) in nonce.iter_mut().zip(self.iv.iter()) {
*nonce ^= inp;
}
let tag_pos = payload.len() - AES128_TAG_LEN;
let (buffer, tag) = payload.split_at_mut(tag_pos);
let taga = GenericArray::from_slice(tag);
self.key
.decrypt_in_place_detached(GenericArray::from_slice(&nonce), header, buffer, taga)
.map_err(|_| ())?;
Ok(&payload[..tag_pos])
}
}
pub struct DirectionalKeys {
pub header: HeaderProtectionKey,
pub packet: PacketKey,
}
impl DirectionalKeys {
fn new(secret: &[u8], version: u32) -> Self {
Self {
header: HeaderProtectionKey::new(secret, version),
packet: PacketKey::new(secret, version),
}
}
}
pub struct QuicKeys {
pub local: DirectionalKeys,
pub remote: DirectionalKeys,
}
fn hkdf_expand_label(hk: &Hkdf<Sha256>, label: &[u8], okm: &mut [u8], olen: u16) {
const LABEL_PREFIX: &[u8] = b"tls13 ";
let output_len = u16::to_be_bytes(olen);
let label_len = u8::to_be_bytes((LABEL_PREFIX.len() + label.len()) as u8);
let context_len = u8::to_be_bytes(0);
let info = &[
&output_len[..],
&label_len[..],
LABEL_PREFIX,
label,
&context_len[..],
];
hk.expand_multi_info(info, okm).unwrap();
}
pub fn quic_keys_initial(version: u32, client_dst_connection_id: &[u8]) -> Option<QuicKeys> {
let salt = match version {
0x51303530 => &[
0x50, 0x45, 0x74, 0xEF, 0xD0, 0x66, 0xFE, 0x2F, 0x9D, 0x94, 0x5C, 0xFC, 0xDB, 0xD3,
0xA7, 0xF0, 0xD3, 0xB5, 0x6B, 0x45,
],
0xff00_001d..=0xff00_0020 => &[
// https://datatracker.ietf.org/doc/html/draft-ietf-quic-tls-32#section-5.2
0xaf, 0xbf, 0xec, 0x28, 0x99, 0x93, 0xd2, 0x4c, 0x9e, 0x97, 0x86, 0xf1, 0x9c, 0x61,
0x11, 0xe0, 0x43, 0x90, 0xa8, 0x99,
],
0xfaceb002 | 0xff00_0017..=0xff00_001c => &[
// https://datatracker.ietf.org/doc/html/draft-ietf-quic-tls-23#section-5.2
0xc3, 0xee, 0xf7, 0x12, 0xc7, 0x2e, 0xbb, 0x5a, 0x11, 0xa7, 0xd2, 0x43, 0x2b, 0xb4,
0x63, 0x65, 0xbe, 0xf9, 0xf5, 0x02,
],
0x0000_0001 | 0xff00_0021..=0xff00_0022 => &[
// https://www.rfc-editor.org/rfc/rfc9001.html#name-initial-secrets
0x38, 0x76, 0x2c, 0xf7, 0xf5, 0x59, 0x34, 0xb3, 0x4d, 0x17, 0x9a, 0xe6, 0xa4, 0xc8,
0x0c, 0xad, 0xcc, 0xbb, 0x7f, 0x0a,
],
0x6b3343cf => &[
// https://www.rfc-editor.org/rfc/rfc9369.html#section-3.3.1
0x0d, 0xed, 0xe3, 0xde, 0xf7, 0x00, 0xa6, 0xdb, 0x81, 0x93, 0x81, 0xbe, 0x6e, 0x26,
0x9d, 0xcb, 0xf9, 0xbd, 0x2e, 0xd9,
],
_ => {
return None;
}
};
let hk = Hkdf::<Sha256>::new(Some(salt), client_dst_connection_id);
let mut client_secret = [0u8; 32];
hkdf_expand_label(&hk, b"client in", &mut client_secret, 32);
let mut server_secret = [0u8; 32];
hkdf_expand_label(&hk, b"server in", &mut server_secret, 32);
return Some(QuicKeys {
local: DirectionalKeys::new(&server_secret, version),
remote: DirectionalKeys::new(&client_secret, version),
});
}
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