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active fingerprinting detection and blocking

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This commit is contained in:
Alexander Bersenev
2019-04-20 04:44:11 +05:00
parent 830d55fe77
commit 4cae6290b9
1 changed files with 24 additions and 6 deletions
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30
mtprotoproxy.py
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@@ -43,6 +43,9 @@ FAST_MODE = config.get("FAST_MODE", True)
# doesn't allow to connect in not-secure mode
SECURE_ONLY = config.get("SECURE_ONLY", False)
# length of used handshake randoms for active fingerprinting protection
REPLAY_CHECK_LEN = config.get("REPLAY_CHECK_LEN", 32768)
# delay in seconds between stats printing
STATS_PRINT_PERIOD = config.get("STATS_PRINT_PERIOD", 600)
@@ -130,7 +133,7 @@ MIN_MSG_LEN = 12
MAX_MSG_LEN = 2 ** 24
my_ip_info = {"ipv4": None, "ipv6": None}
used_handshakes = collections.OrderedDict()
def setup_files_limit():
try:
@@ -601,18 +604,30 @@ class ProxyReqStreamWriter(LayeredStreamWriterBase):
async def handle_handshake(reader, writer):
global used_handshakes
EMPTY_READ_BUF_SIZE = 4096
handshake = await reader.readexactly(HANDSHAKE_LEN)
dec_prekey_and_iv = handshake[SKIP_LEN:SKIP_LEN+PREKEY_LEN+IV_LEN]
dec_prekey, dec_iv = dec_prekey_and_iv[:PREKEY_LEN], dec_prekey_and_iv[PREKEY_LEN:]
enc_prekey_and_iv = handshake[SKIP_LEN:SKIP_LEN+PREKEY_LEN+IV_LEN][::-1]
enc_prekey, enc_iv = enc_prekey_and_iv[:PREKEY_LEN], enc_prekey_and_iv[PREKEY_LEN:]
if dec_prekey_and_iv in used_handshakes:
ip = writer.get_extra_info('peername')[0]
print_err("Active fingerprinting detected from %s, freezing it" % ip)
while await reader.read(EMPTY_READ_BUF_SIZE):
# just consume all the data
pass
return False
for user in USERS:
secret = bytes.fromhex(USERS[user])
dec_prekey_and_iv = handshake[SKIP_LEN:SKIP_LEN+PREKEY_LEN+IV_LEN]
dec_prekey, dec_iv = dec_prekey_and_iv[:PREKEY_LEN], dec_prekey_and_iv[PREKEY_LEN:]
dec_key = hashlib.sha256(dec_prekey + secret).digest()
decryptor = create_aes_ctr(key=dec_key, iv=int.from_bytes(dec_iv, "big"))
enc_prekey_and_iv = handshake[SKIP_LEN:SKIP_LEN+PREKEY_LEN+IV_LEN][::-1]
enc_prekey, enc_iv = enc_prekey_and_iv[:PREKEY_LEN], enc_prekey_and_iv[PREKEY_LEN:]
enc_key = hashlib.sha256(enc_prekey + secret).digest()
encryptor = create_aes_ctr(key=enc_key, iv=int.from_bytes(enc_iv, "big"))
@@ -627,11 +642,14 @@ async def handle_handshake(reader, writer):
dc_idx = int.from_bytes(decrypted[DC_IDX_POS:DC_IDX_POS+2], "little", signed=True)
while len(used_handshakes) >= REPLAY_CHECK_LEN:
used_handshakes.popitem(last=False)
used_handshakes[dec_prekey_and_iv] = True
reader = CryptoWrappedStreamReader(reader, decryptor)
writer = CryptoWrappedStreamWriter(writer, encryptor)
return reader, writer, proto_tag, user, dc_idx, enc_key + enc_iv
EMPTY_READ_BUF_SIZE = 4096
while await reader.read(EMPTY_READ_BUF_SIZE):
# just consume all the data
pass