66 lines
2.5 KiB
Python
66 lines
2.5 KiB
Python
# Pyrogram - Telegram MTProto API Client Library for Python
|
|
# Copyright (C) 2017-2018 Dan Tès <https://github.com/delivrance>
|
|
#
|
|
# This file is part of Pyrogram.
|
|
#
|
|
# Pyrogram is free software: you can redistribute it and/or modify
|
|
# it under the terms of the GNU Lesser General Public License as published
|
|
# by the Free Software Foundation, either version 3 of the License, or
|
|
# (at your option) any later version.
|
|
#
|
|
# Pyrogram is distributed in the hope that it will be useful,
|
|
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
# GNU Lesser General Public License for more details.
|
|
#
|
|
# You should have received a copy of the GNU Lesser General Public License
|
|
# along with Pyrogram. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
from hashlib import sha256
|
|
from io import BytesIO
|
|
from os import urandom
|
|
|
|
from pyrogram.api.core import Message, Long
|
|
from . import AES, KDF
|
|
|
|
|
|
class MTProto:
|
|
INITIAL_SALT = 0x616e67656c696361
|
|
|
|
@staticmethod
|
|
def pack(message: Message, salt: int, session_id: bytes, auth_key: bytes, auth_key_id: bytes) -> bytes:
|
|
data = Long(salt) + session_id + message.write()
|
|
padding = urandom(-(len(data) + 12) % 16 + 12)
|
|
|
|
# 88 = 88 + 0 (outgoing message)
|
|
msg_key_large = sha256(auth_key[88: 88 + 32] + data + padding).digest()
|
|
msg_key = msg_key_large[8:24]
|
|
aes_key, aes_iv = KDF(auth_key, msg_key, True)
|
|
|
|
return auth_key_id + msg_key + AES.ige256_encrypt(data + padding, aes_key, aes_iv)
|
|
|
|
@staticmethod
|
|
def unpack(b: BytesIO, salt: int, session_id: bytes, auth_key: bytes, auth_key_id: bytes) -> Message:
|
|
assert b.read(8) == auth_key_id, b.getvalue()
|
|
|
|
msg_key = b.read(16)
|
|
aes_key, aes_iv = KDF(auth_key, msg_key, False)
|
|
data = BytesIO(AES.ige256_decrypt(b.read(), aes_key, aes_iv))
|
|
|
|
assert data.read(8) == Long(salt) or Long(salt) == Long(MTProto.INITIAL_SALT)
|
|
|
|
# https://core.telegram.org/mtproto/security_guidelines#checking-session-id
|
|
assert data.read(8) == session_id
|
|
|
|
message = Message.read(data)
|
|
|
|
# https://core.telegram.org/mtproto/security_guidelines#checking-sha256-hash-value-of-msg-key
|
|
# https://core.telegram.org/mtproto/security_guidelines#checking-message-length
|
|
# 96 = 88 + 8 (incoming message)
|
|
assert msg_key == sha256(auth_key[96:96 + 32] + data.getvalue()).digest()[8:24]
|
|
|
|
# https://core.telegram.org/mtproto/security_guidelines#checking-msg-id
|
|
assert message.msg_id % 2 != 0
|
|
|
|
return message
|