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generate proper nounces

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Alexander Bersenev
2018-05-28 18:35:00 +05:00
parent 8494b17599
commit 812298d705
1 changed files with 23 additions and 10 deletions
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33
mtprotoproxy.py
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@@ -44,7 +44,10 @@ SKIP_LEN = 8
PREKEY_LEN = 32
KEY_LEN = 32
IV_LEN = 16
HANDSHAKE_LEN = 64
MAGIC_VAL_POS = 56
MAGIC_VAL_TO_CHECK = b'\xef\xef\xef\xef'
def init_stats():
global stats
@@ -62,7 +65,7 @@ def update_stats(user, connects=0, curr_connects_x2=0, octets=0):
async def handle_handshake(reader, writer):
handshake = await reader.readexactly(64)
handshake = await reader.readexactly(HANDSHAKE_LEN)
for user in USERS:
secret = bytes.fromhex(USERS[user])
@@ -79,9 +82,8 @@ async def handle_handshake(reader, writer):
decrypted = decryptor.decrypt(handshake)
MAGIC_VAL = b'\xef\xef\xef\xef'
check_val = decrypted[56:60]
if check_val != MAGIC_VAL:
check_val = decrypted[MAGIC_VAL_POS:MAGIC_VAL_POS+4]
if check_val != MAGIC_VAL_TO_CHECK:
continue
dc_idx = abs(int.from_bytes(decrypted[60:62], "little", signed=True)) - 1
@@ -96,6 +98,11 @@ async def handle_handshake(reader, writer):
async def do_handshake(dc, dec_key_and_iv=None):
RESERVED_NONCE_FIRST_CHARS = [b"\xef"]
RESERVED_NONCE_BEGININGS = [b"\x48\x45\x41\x44", b"\x50\x4F\x53\x54",
b"\x47\x45\x54\x20", b"\xee\xee\xee\xee"]
RESERVED_NONCE_CONTINUES = [b"\x00\x00\x00\x00"]
try:
reader_tgt, writer_tgt = await asyncio.open_connection(dc, TG_DATACENTER_PORT)
except ConnectionRefusedError as E:
@@ -103,11 +110,17 @@ async def do_handshake(dc, dec_key_and_iv=None):
except OSError as E:
return False
rnd = bytearray([random.randrange(0, 256) for i in range(64)])
rnd[56] = 0xef
rnd[57] = 0xef
rnd[58] = 0xef
rnd[59] = 0xef
while True:
rnd = bytearray([random.randrange(0, 256) for i in range(HANDSHAKE_LEN)])
if rnd[:1] in RESERVED_NONCE_FIRST_CHARS:
continue
if rnd[:4] in RESERVED_NONCE_BEGININGS:
continue
if rnd[4:8] in RESERVED_NONCE_CONTINUES:
continue
break
rnd[MAGIC_VAL_POS:MAGIC_VAL_POS+4] = MAGIC_VAL_TO_CHECK
if dec_key_and_iv:
rnd[SKIP_LEN:SKIP_LEN+KEY_LEN+IV_LEN] = dec_key_and_iv[::-1]
@@ -122,7 +135,7 @@ async def do_handshake(dc, dec_key_and_iv=None):
enc_key, enc_iv = enc_key_and_iv[:KEY_LEN], enc_key_and_iv[KEY_LEN:]
encryptor = create_aes(key=enc_key, iv=int.from_bytes(enc_iv, "big"))
rnd_enc = rnd[:56] + encryptor.encrypt(rnd)[56:]
rnd_enc = rnd[:MAGIC_VAL_POS] + encryptor.encrypt(rnd)[MAGIC_VAL_POS:]
writer_tgt.write(rnd_enc)
await writer_tgt.drain()