2017-12-19 12:59:15 +00:00
|
|
|
# Pyrogram - Telegram MTProto API Client Library for Python
|
2018-01-01 12:21:23 +00:00
|
|
|
# Copyright (C) 2017-2018 Dan Tès <https://github.com/delivrance>
|
2017-12-19 12:59:15 +00:00
|
|
|
#
|
|
|
|
|
# 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/>.
|
|
|
|
|
|
|
|
|
|
try:
|
|
|
|
|
from pyaes import AESModeOfOperationCTR
|
|
|
|
|
except ImportError:
|
|
|
|
|
pass
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class CTR:
|
|
|
|
|
def __init__(self, key: bytes, iv: bytes):
|
|
|
|
|
self.ctr = AESModeOfOperationCTR(key)
|
|
|
|
|
self.iv = iv
|
|
|
|
|
|
|
|
|
|
def decrypt(self, data: bytes, offset: int) -> bytes:
|
|
|
|
|
replace = int.to_bytes(offset // 16, byteorder="big", length=4)
|
|
|
|
|
iv = self.iv[:-4] + replace
|
|
|
|
|
self.ctr._counter._counter = list(iv)
|
|
|
|
|
|
|
|
|
|
return self.ctr.decrypt(data)
|
