Telethon/telethon/network/connection/tcpobfuscated.py
2019-03-10 03:26:24 +01:00

70 lines
2.3 KiB
Python

import os
from .tcpabridged import AbridgedPacket
from .connection import Connection
from ...crypto import AESModeCTR
class ConnectionTcpObfuscated(Connection):
"""
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.
"""
def __init__(self, ip, port, dc_id, *, loop, loggers, proxy=None):
super().__init__(
ip, port, dc_id, loop=loop, loggers=loggers, proxy=proxy)
self._codec = AbridgedPacket()
def _init_conn(self):
self._obfuscation = ObfuscatedIO(
self._reader, self._writer, self._codec.mtproto_proxy_tag)
self._writer.write(self._obfuscation.header)
def _send(self, data):
self._obfuscation.write(self._codec.encode_packet(data))
async def _recv(self):
return await self._codec.read_packet(self._obfuscation)
class ObfuscatedIO:
header = None
def __init__(self, reader, writer, protocol_tag):
self._reader = reader
self._writer = writer
# 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])
self._aes_encrypt = AESModeCTR(encrypt_key, encrypt_iv)
self._aes_decrypt = AESModeCTR(decrypt_key, decrypt_iv)
random[56:60] = protocol_tag
random[56:64] = self._aes_encrypt.encrypt(bytes(random))[56:64]
self.header = random
async def readexactly(self, n):
return self._aes_decrypt.encrypt(await self._reader.readexactly(n))
def write(self, data):
self._writer.write(self._aes_encrypt.encrypt(data))