2020-03-21 14:43:32 +00:00
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# Pyrogram - Telegram MTProto API Client Library for Python
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# Copyright (C) 2017-2020 Dan <https://github.com/delivrance>
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2017-12-05 11:39:04 +00:00
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#
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2020-03-21 14:43:32 +00:00
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# This file is part of Pyrogram.
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2017-12-05 11:39:04 +00:00
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#
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2020-03-21 14:43:32 +00:00
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# Pyrogram is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License as published
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# by the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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2017-12-05 11:39:04 +00:00
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#
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2020-03-21 14:43:32 +00:00
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# Pyrogram is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Lesser General Public License for more details.
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2017-12-05 11:39:04 +00:00
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#
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2020-03-21 14:43:32 +00:00
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# You should have received a copy of the GNU Lesser General Public License
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# along with Pyrogram. If not, see <http://www.gnu.org/licenses/>.
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2017-12-05 11:39:04 +00:00
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2017-12-09 01:25:14 +00:00
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from hashlib import sha256
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2017-12-05 11:39:04 +00:00
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2017-12-18 14:16:21 +00:00
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class KDF:
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2017-12-09 00:10:09 +00:00
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def __new__(cls, auth_key: bytes, msg_key: bytes, outgoing: bool) -> tuple:
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# https://core.telegram.org/mtproto/description#defining-aes-key-and-initialization-vector
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x = 0 if outgoing else 8
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sha256_a = sha256(msg_key + auth_key[x: x + 36]).digest()
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sha256_b = sha256(auth_key[x + 40:x + 76] + msg_key).digest() # 76 = 40 + 36
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aes_key = sha256_a[:8] + sha256_b[8:24] + sha256_a[24:32]
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aes_iv = sha256_b[:8] + sha256_a[8:24] + sha256_b[24:32]
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return aes_key, aes_iv
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