Telethon/telethon/network/connection/tcpobfuscated.py
2019-03-12 01:12:55 +01:00

62 lines
1.9 KiB
Python

import os
from .tcpabridged import AbridgedPacketCodec
from .connection import ObfuscatedConnection
from ...crypto import AESModeCTR
class ObfuscatedIO:
header = None
def __init__(self, connection):
self._reader = connection._reader
self._writer = connection._writer
(self.header,
self._encrypt,
self._decrypt) = self.init_header(connection.packet_codec)
def init_header(self, packet_codec):
# Obfuscated messages secrets cannot start with any of these
keywords = (b'PVrG', b'GET ', b'POST', b'\xee\xee\xee\xee')
while True:
random = os.urandom(64)
if (random[0] != 0xef and
random[:4] not in keywords and
random[4:4] != b'\0\0\0\0'):
break
random = bytearray(random)
random_reversed = random[55:7:-1] # Reversed (8, len=48)
# Encryption has "continuous buffer" enabled
encrypt_key = bytes(random[8:40])
encrypt_iv = bytes(random[40:56])
decrypt_key = bytes(random_reversed[:32])
decrypt_iv = bytes(random_reversed[32:48])
encryptor = AESModeCTR(encrypt_key, encrypt_iv)
decryptor = AESModeCTR(decrypt_key, decrypt_iv)
random[56:60] = packet_codec.obfuscate_tag
random[56:64] = encryptor.encrypt(bytes(random))[56:64]
return (random, encryptor, decryptor)
async def readexactly(self, n):
return self._decrypt.encrypt(await self._reader.readexactly(n))
def write(self, data):
self._writer.write(self._encrypt.encrypt(data))
class ConnectionTcpObfuscated(ObfuscatedConnection):
"""
Mode that Telegram defines as "obfuscated2". Encodes the packet
just like `ConnectionTcpAbridged`, but encrypts every message with
a randomly generated key using the AES-CTR mode so the packets are
harder to discern.
"""
obfuscated_io = ObfuscatedIO
packet_codec = AbridgedPacketCodec