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Generate Valid X25519MLKEM768 ServerHello key shares

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Co-Authored-By: brekotis <93345790+brekotis@users.noreply.github.com>
This commit is contained in:
Alexey
2026-06-11 14:14:09 +03:00
parent eba55e755d
commit 62af515504
9 changed files with 477 additions and 70 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/tls_front/emulator.rs
+28 -10
View File
@@ -7,7 +7,6 @@ use crate::protocol::constants::{
};
use crate::protocol::tls::{
ClientHelloTlsVersion, TLS_DIGEST_LEN, TLS_DIGEST_POS, TLS_NAMED_GROUP_X25519MLKEM768,
gen_fake_x25519mlkem768_server_key_share,
};
use crate::tls_front::types::{
CachedTlsData, ParsedCertificateInfo, TlsExtension, TlsProfileSource,
@@ -209,15 +208,18 @@ fn push_key_share_entry(extensions: &mut Vec<u8>, group: u16, key_exchange: &[u8
extensions.extend_from_slice(key_exchange);
}
fn push_key_share_extension(extensions: &mut Vec<u8>, rng: &SecureRandom) {
let key = gen_fake_x25519mlkem768_server_key_share(rng);
push_key_share_entry(extensions, TLS_NAMED_GROUP_X25519MLKEM768, &key);
fn push_key_share_extension(extensions: &mut Vec<u8>, server_key_share: &[u8]) {
push_key_share_entry(
extensions,
TLS_NAMED_GROUP_X25519MLKEM768,
server_key_share,
);
}
fn replay_profiled_server_hello_extension(
ext: &TlsExtension,
extensions: &mut Vec<u8>,
rng: &SecureRandom,
server_key_share: &[u8],
saw_supported_versions: &mut bool,
saw_key_share: &mut bool,
) {
@@ -227,7 +229,7 @@ fn replay_profiled_server_hello_extension(
*saw_supported_versions = true;
}
EXT_KEY_SHARE if !*saw_key_share => {
push_key_share_extension(extensions, rng);
push_key_share_extension(extensions, server_key_share);
*saw_key_share = true;
}
EXT_ALPN => {}
@@ -235,7 +237,10 @@ fn replay_profiled_server_hello_extension(
}
}
fn build_profiled_server_hello_extensions(cached: &CachedTlsData, rng: &SecureRandom) -> Vec<u8> {
fn build_profiled_server_hello_extensions(
cached: &CachedTlsData,
server_key_share: &[u8],
) -> Vec<u8> {
let capacity = cached
.server_hello_template
.extensions
@@ -251,14 +256,14 @@ fn build_profiled_server_hello_extensions(cached: &CachedTlsData, rng: &SecureRa
replay_profiled_server_hello_extension(
ext,
&mut extensions,
rng,
server_key_share,
&mut saw_supported_versions,
&mut saw_key_share,
);
}
if !saw_key_share {
push_key_share_extension(&mut extensions, rng);
push_key_share_extension(&mut extensions, server_key_share);
}
if !saw_supported_versions {
push_supported_versions_extension(&mut extensions);
@@ -277,12 +282,13 @@ pub fn build_emulated_server_hello(
serverhello_compact: bool,
client_tls_version: ClientHelloTlsVersion,
selected_cipher_suite: [u8; 2],
server_key_share: &[u8],
rng: &SecureRandom,
alpn: Option<Vec<u8>>,
new_session_tickets: u8,
) -> Vec<u8> {
// --- ServerHello ---
let extensions = build_profiled_server_hello_extensions(cached, rng);
let extensions = build_profiled_server_hello_extensions(cached, server_key_share);
let extensions_len = extensions.len() as u16;
let body_len = 2 + 32 + 1 + session_id.len() + 2 + 1 + 2 + extensions.len();
@@ -534,6 +540,10 @@ mod tests {
}
}
fn test_server_key_share() -> Vec<u8> {
vec![0x42; 1120]
}
#[test]
fn test_build_emulated_server_hello_uses_cached_cert_payload() {
let cert_msg = vec![0x0b, 0x00, 0x00, 0x05, 0x00, 0xaa, 0xbb, 0xcc, 0xdd];
@@ -551,6 +561,7 @@ mod tests {
true,
ClientHelloTlsVersion::Tls12,
[0x13, 0x01],
&test_server_key_share(),
&rng,
None,
0,
@@ -580,6 +591,7 @@ mod tests {
true,
ClientHelloTlsVersion::Tls13,
[0x13, 0x03],
&test_server_key_share(),
&rng,
None,
0,
@@ -615,6 +627,7 @@ mod tests {
true,
ClientHelloTlsVersion::Tls13,
[0x13, 0x01],
&test_server_key_share(),
&rng,
Some(b"h2".to_vec()),
0,
@@ -639,6 +652,7 @@ mod tests {
true,
ClientHelloTlsVersion::Tls12,
[0x13, 0x01],
&test_server_key_share(),
&rng,
None,
0,
@@ -674,6 +688,7 @@ mod tests {
true,
ClientHelloTlsVersion::Tls12,
[0x13, 0x01],
&test_server_key_share(),
&rng,
None,
0,
@@ -715,6 +730,7 @@ mod tests {
true,
ClientHelloTlsVersion::Tls13,
[0x13, 0x01],
&test_server_key_share(),
&rng,
None,
0,
@@ -748,6 +764,7 @@ mod tests {
false,
ClientHelloTlsVersion::Tls12,
[0x13, 0x01],
&test_server_key_share(),
&rng,
Some(b"h2".to_vec()),
0,
@@ -780,6 +797,7 @@ mod tests {
true,
ClientHelloTlsVersion::Tls13,
[0x13, 0x01],
&test_server_key_share(),
&rng,
None,
0,
src/tls_front/fetcher.rs
+102 -17
View File
@@ -9,6 +9,9 @@ use std::sync::atomic::{AtomicU64, Ordering};
use std::time::{Duration, Instant};
use anyhow::{Result, anyhow};
use ml_kem::{
DecapsulationKey as MlKemDecapsulationKey, KeyExport, MlKem768, Seed as MlKemSeed,
};
use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
use tokio::net::TcpStream;
#[cfg(unix)]
@@ -33,6 +36,7 @@ use crate::network::dns_overrides::resolve_socket_addr;
use crate::protocol::constants::{
TLS_RECORD_APPLICATION, TLS_RECORD_CHANGE_CIPHER, TLS_RECORD_HANDSHAKE,
};
use crate::protocol::tls::{TLS_NAMED_GROUP_X25519, TLS_NAMED_GROUP_X25519MLKEM768};
use crate::tls_front::types::{
ParsedCertificateInfo, ParsedServerHello, TlsBehaviorProfile, TlsCertPayload, TlsExtension,
TlsFetchResult, TlsProfileSource,
@@ -40,6 +44,10 @@ use crate::tls_front::types::{
use crate::transport::UpstreamStream;
use crate::transport::proxy_protocol::{ProxyProtocolV1Builder, ProxyProtocolV2Builder};
#[cfg(test)]
const X25519_KEY_SHARE_LEN: usize = 32;
const MLKEM768_CLIENT_ENCAPSULATION_KEY_LEN: usize = 1184;
/// No-op verifier: accept any certificate (we only need lengths and metadata).
#[derive(Debug)]
struct NoVerify;
@@ -393,8 +401,13 @@ fn profile_cipher_suites(profile: TlsFetchProfile) -> &'static [u16] {
}
fn profile_groups(profile: TlsFetchProfile) -> &'static [u16] {
const MODERN: &[u16] = &[0x001d, 0x0017, 0x0018]; // x25519, secp256r1, secp384r1
const COMPAT: &[u16] = &[0x001d, 0x0017];
const MODERN: &[u16] = &[
TLS_NAMED_GROUP_X25519MLKEM768,
TLS_NAMED_GROUP_X25519,
0x0017,
0x0018,
];
const COMPAT: &[u16] = &[TLS_NAMED_GROUP_X25519, 0x0017];
const LEGACY: &[u16] = &[0x0017];
match profile {
@@ -475,6 +488,50 @@ fn grease_value(rng: &SecureRandom, deterministic: bool, seed: &str) -> u16 {
}
}
fn gen_mlkem768_client_encapsulation_key(
rng: &SecureRandom,
deterministic: bool,
seed: &str,
) -> Option<Vec<u8>> {
let seed_bytes = if deterministic {
deterministic_bytes(seed, 64)
} else {
rng.bytes(64)
};
let seed = MlKemSeed::try_from(seed_bytes.as_slice()).ok()?;
let decapsulation_key = MlKemDecapsulationKey::<MlKem768>::from_seed(seed);
let encapsulation_key = decapsulation_key.encapsulation_key().to_bytes();
let bytes = encapsulation_key.as_slice();
if bytes.len() == MLKEM768_CLIENT_ENCAPSULATION_KEY_LEN {
Some(bytes.to_vec())
} else {
None
}
}
fn gen_x25519mlkem768_client_key_share(
rng: &SecureRandom,
deterministic: bool,
seed: &str,
) -> Option<Vec<u8>> {
let mlkem_key = gen_mlkem768_client_encapsulation_key(
rng,
deterministic,
&format!("{seed}:mlkem768"),
)?;
let x25519_key = gen_key_share(rng, deterministic, &format!("{seed}:x25519"));
let mut key_share = Vec::with_capacity(MLKEM768_CLIENT_ENCAPSULATION_KEY_LEN + x25519_key.len());
key_share.extend_from_slice(&mlkem_key);
key_share.extend_from_slice(&x25519_key);
Some(key_share)
}
fn push_client_key_share_entry(keyshare: &mut Vec<u8>, group: u16, key: &[u8]) {
keyshare.extend_from_slice(&group.to_be_bytes());
keyshare.extend_from_slice(&(key.len() as u16).to_be_bytes());
keyshare.extend_from_slice(key);
}
fn build_client_hello(
sni: &str,
rng: &SecureRandom,
@@ -597,16 +654,21 @@ fn build_client_hello(
push_extension(0x002d, &[0x01, 0x01]);
}
// key_share (x25519)
let key = gen_key_share(
rng,
deterministic,
&format!("tls-fetch-keyshare:{sni}:{}", profile.as_str()),
);
let mut keyshare = Vec::with_capacity(4 + key.len());
keyshare.extend_from_slice(&0x001du16.to_be_bytes());
keyshare.extend_from_slice(&(key.len() as u16).to_be_bytes());
keyshare.extend_from_slice(&key);
// key_share
let key_share_seed = format!("tls-fetch-keyshare:{sni}:{}", profile.as_str());
let mut keyshare = Vec::new();
if matches!(
profile,
TlsFetchProfile::ModernChromeLike | TlsFetchProfile::ModernFirefoxLike
) {
if let Some(key) =
gen_x25519mlkem768_client_key_share(rng, deterministic, &key_share_seed)
{
push_client_key_share_entry(&mut keyshare, TLS_NAMED_GROUP_X25519MLKEM768, &key);
}
}
let key = gen_key_share(rng, deterministic, &key_share_seed);
push_client_key_share_entry(&mut keyshare, TLS_NAMED_GROUP_X25519, &key);
let mut keyshare_ext = Vec::with_capacity(2 + keyshare.len());
keyshare_ext.extend_from_slice(&(keyshare.len() as u16).to_be_bytes());
keyshare_ext.extend_from_slice(&keyshare);
@@ -1788,11 +1850,34 @@ mod tests {
key_share_data.len() - 2,
"key_share list length mismatch"
);
let group = u16::from_be_bytes([key_share_data[2], key_share_data[3]]);
let key_len = u16::from_be_bytes([key_share_data[4], key_share_data[5]]) as usize;
let key = &key_share_data[6..6 + key_len];
assert_eq!(group, 0x001d, "key_share group must be x25519");
assert_eq!(key_len, 32, "x25519 key length must be 32");
let mut pos = 2usize;
let hybrid_group = u16::from_be_bytes([key_share_data[pos], key_share_data[pos + 1]]);
let hybrid_len =
u16::from_be_bytes([key_share_data[pos + 2], key_share_data[pos + 3]]) as usize;
pos += 4;
let hybrid_key = &key_share_data[pos..pos + hybrid_len];
pos += hybrid_len;
assert_eq!(
hybrid_group, TLS_NAMED_GROUP_X25519MLKEM768,
"first key_share group must be X25519MLKEM768"
);
assert_eq!(
hybrid_len,
MLKEM768_CLIENT_ENCAPSULATION_KEY_LEN + X25519_KEY_SHARE_LEN,
"hybrid key length must match X25519MLKEM768"
);
assert!(
hybrid_key.iter().any(|b| *b != 0),
"hybrid key must not be all zero"
);
let group = u16::from_be_bytes([key_share_data[pos], key_share_data[pos + 1]]);
let key_len =
u16::from_be_bytes([key_share_data[pos + 2], key_share_data[pos + 3]]) as usize;
pos += 4;
let key = &key_share_data[pos..pos + key_len];
assert_eq!(group, TLS_NAMED_GROUP_X25519, "second key_share group must be x25519");
assert_eq!(key_len, X25519_KEY_SHARE_LEN, "x25519 key length must be 32");
assert!(
key.iter().any(|b| *b != 0),
"x25519 key must not be all zero"
src/tls_front/tests/emulator_profile_fidelity_security_tests.rs
+7
View File
@@ -52,6 +52,10 @@ fn record_lengths_by_type(response: &[u8], wanted_type: u8) -> Vec<usize> {
out
}
fn test_server_key_share() -> Vec<u8> {
vec![0x42; 1120]
}
#[test]
fn emulated_server_hello_keeps_single_change_cipher_spec_for_client_compatibility() {
let cached = make_cached();
@@ -66,6 +70,7 @@ fn emulated_server_hello_keeps_single_change_cipher_spec_for_client_compatibilit
true,
ClientHelloTlsVersion::Tls13,
[0x13, 0x01],
&test_server_key_share(),
&rng,
None,
0,
@@ -91,6 +96,7 @@ fn emulated_server_hello_does_not_emit_profile_ticket_tail_when_disabled() {
true,
ClientHelloTlsVersion::Tls13,
[0x13, 0x01],
&test_server_key_share(),
&rng,
None,
0,
@@ -114,6 +120,7 @@ fn emulated_server_hello_uses_profile_ticket_lengths_when_enabled() {
true,
ClientHelloTlsVersion::Tls13,
[0x13, 0x01],
&test_server_key_share(),
&rng,
None,
2,
src/tls_front/tests/emulator_security_tests.rs
+7
View File
@@ -44,6 +44,10 @@ fn first_app_data_payload(response: &[u8]) -> &[u8] {
&response[app_start + 5..app_start + 5 + app_len]
}
fn test_server_key_share() -> Vec<u8> {
vec![0x42; 1120]
}
#[test]
fn emulated_server_hello_ignores_oversized_alpn_when_marker_would_not_fit() {
let cached = make_cached(None);
@@ -59,6 +63,7 @@ fn emulated_server_hello_ignores_oversized_alpn_when_marker_would_not_fit() {
true,
ClientHelloTlsVersion::Tls13,
[0x13, 0x01],
&test_server_key_share(),
&rng,
Some(oversized_alpn),
0,
@@ -98,6 +103,7 @@ fn emulated_server_hello_keeps_alpn_marker_out_of_appdata() {
true,
ClientHelloTlsVersion::Tls13,
[0x13, 0x01],
&test_server_key_share(),
&rng,
Some(b"h2".to_vec()),
0,
@@ -129,6 +135,7 @@ fn emulated_server_hello_prefers_cert_payload_over_alpn_marker() {
true,
ClientHelloTlsVersion::Tls12,
[0x13, 0x01],
&test_server_key_share(),
&rng,
Some(b"h2".to_vec()),
0,