mirror of
https://github.com/LonamiWebs/Telethon.git
synced 2024-09-21 03:08:49 +03:00
75 lines
2.4 KiB
Python
75 lines
2.4 KiB
Python
import os
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from hashlib import sha1
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try:
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from Crypto.PublicKey import RSA
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except ImportError:
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raise ImportError('Missing module "pycrypto", please install via pip.')
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from ..extensions import BinaryWriter
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# {fingerprint: Crypto.PublicKey.RSA._RSAobj} dictionary
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_server_keys = { }
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def get_byte_array(integer):
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"""Return the variable length bytes corresponding to the given int"""
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# Operate in big endian (unlike most of Telegram API) since:
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# > "...pq is a representation of a natural number
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# (in binary *big endian* format)..."
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# > "...current value of dh_prime equals
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# (in *big-endian* byte order)..."
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# Reference: https://core.telegram.org/mtproto/auth_key
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return int.to_bytes(
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integer,
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length=(integer.bit_length() + 8 - 1) // 8, # 8 bits per byte,
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byteorder='big',
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signed=False
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)
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def _compute_fingerprint(key):
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"""For a given Crypto.RSA key, computes its 8-bytes-long fingerprint
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in the same way that Telegram does.
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"""
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with BinaryWriter() as writer:
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writer.tgwrite_bytes(get_byte_array(key.n))
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writer.tgwrite_bytes(get_byte_array(key.e))
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# Telegram uses the last 8 bytes as the fingerprint
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return sha1(writer.get_bytes()).digest()[-8:]
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def add_key(pub):
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"""Adds a new public key to be used when encrypting new data is needed"""
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global _server_keys
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key = RSA.importKey(pub)
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_server_keys[_compute_fingerprint(key)] = key
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def encrypt(fingerprint, data):
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"""Given the fingerprint of a previously added RSA key, encrypt its data
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in the way Telegram requires us to do so (sha1(data) + data + padding)
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"""
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global _server_keys
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key = _server_keys.get(fingerprint, None)
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if not key:
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return None
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# len(sha1.digest) is always 20, so we're left with 255 - 20 - x padding
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to_encrypt = sha1(data).digest() + data + os.urandom(235 - len(data))
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return key.encrypt(to_encrypt, 0)[0]
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# Add default keys
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for pub in (
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'''-----BEGIN RSA PUBLIC KEY-----
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MIIBCgKCAQEAwVACPi9w23mF3tBkdZz+zwrzKOaaQdr01vAbU4E1pvkfj4sqDsm6
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lyDONS789sVoD/xCS9Y0hkkC3gtL1tSfTlgCMOOul9lcixlEKzwKENj1Yz/s7daS
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an9tqw3bfUV/nqgbhGX81v/+7RFAEd+RwFnK7a+XYl9sluzHRyVVaTTveB2GazTw
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Efzk2DWgkBluml8OREmvfraX3bkHZJTKX4EQSjBbbdJ2ZXIsRrYOXfaA+xayEGB+
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8hdlLmAjbCVfaigxX0CDqWeR1yFL9kwd9P0NsZRPsmoqVwMbMu7mStFai6aIhc3n
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Slv8kg9qv1m6XHVQY3PnEw+QQtqSIXklHwIDAQAB
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-----END RSA PUBLIC KEY-----''',
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):
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add_key(pub)
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