mirror of
https://github.com/LonamiWebs/Telethon.git
synced 2024-11-29 12:53:44 +03:00
247 lines
9.6 KiB
Python
247 lines
9.6 KiB
Python
import os
|
|
import time
|
|
from hashlib import sha1
|
|
|
|
from .. import helpers as utils
|
|
from ..crypto import AES, RSA, AuthKey, Factorization
|
|
from ..network import MtProtoPlainSender
|
|
from ..extensions import BinaryReader, BinaryWriter
|
|
|
|
|
|
def do_authentication(transport):
|
|
"""Executes the authentication process with the Telegram servers.
|
|
If no error is raised, returns both the authorization key and the
|
|
time offset.
|
|
"""
|
|
sender = MtProtoPlainSender(transport)
|
|
sender.connect()
|
|
|
|
# Step 1 sending: PQ Request
|
|
nonce = os.urandom(16)
|
|
with BinaryWriter() as writer:
|
|
writer.write_int(0x60469778, signed=False) # Constructor number
|
|
writer.write(nonce)
|
|
sender.send(writer.get_bytes())
|
|
|
|
# Step 1 response: PQ Request
|
|
pq, pq_bytes, server_nonce, fingerprints = None, None, None, []
|
|
with BinaryReader(sender.receive()) as reader:
|
|
response_code = reader.read_int(signed=False)
|
|
if response_code != 0x05162463:
|
|
raise AssertionError('Invalid response code: {}'.format(
|
|
hex(response_code)))
|
|
|
|
nonce_from_server = reader.read(16)
|
|
if nonce_from_server != nonce:
|
|
raise AssertionError('Invalid nonce from server')
|
|
|
|
server_nonce = reader.read(16)
|
|
|
|
pq_bytes = reader.tgread_bytes()
|
|
pq = get_int(pq_bytes)
|
|
|
|
vector_id = reader.read_int()
|
|
if vector_id != 0x1cb5c415:
|
|
raise AssertionError('Invalid vector constructor ID: {}'.format(
|
|
hex(response_code)))
|
|
|
|
fingerprints = []
|
|
fingerprint_count = reader.read_int()
|
|
for _ in range(fingerprint_count):
|
|
fingerprints.append(reader.read(8))
|
|
|
|
# Step 2 sending: DH Exchange
|
|
new_nonce = os.urandom(32)
|
|
p, q = Factorization.factorize(pq)
|
|
with BinaryWriter() as pq_inner_data_writer:
|
|
pq_inner_data_writer.write_int(
|
|
0x83c95aec, signed=False) # PQ Inner Data
|
|
pq_inner_data_writer.tgwrite_bytes(get_byte_array(pq, signed=False))
|
|
pq_inner_data_writer.tgwrite_bytes(
|
|
get_byte_array(
|
|
min(p, q), signed=False))
|
|
pq_inner_data_writer.tgwrite_bytes(
|
|
get_byte_array(
|
|
max(p, q), signed=False))
|
|
pq_inner_data_writer.write(nonce)
|
|
pq_inner_data_writer.write(server_nonce)
|
|
pq_inner_data_writer.write(new_nonce)
|
|
|
|
cipher_text, target_fingerprint = None, None
|
|
for fingerprint in fingerprints:
|
|
cipher_text = RSA.encrypt(
|
|
get_fingerprint_text(fingerprint),
|
|
pq_inner_data_writer.get_bytes())
|
|
|
|
if cipher_text is not None:
|
|
target_fingerprint = fingerprint
|
|
break
|
|
|
|
if cipher_text is None:
|
|
raise AssertionError(
|
|
'Could not find a valid key for fingerprints: {}'
|
|
.format(', '.join([get_fingerprint_text(f)
|
|
for f in fingerprints])))
|
|
|
|
with BinaryWriter() as req_dh_params_writer:
|
|
req_dh_params_writer.write_int(
|
|
0xd712e4be, signed=False) # Req DH Params
|
|
req_dh_params_writer.write(nonce)
|
|
req_dh_params_writer.write(server_nonce)
|
|
req_dh_params_writer.tgwrite_bytes(
|
|
get_byte_array(
|
|
min(p, q), signed=False))
|
|
req_dh_params_writer.tgwrite_bytes(
|
|
get_byte_array(
|
|
max(p, q), signed=False))
|
|
req_dh_params_writer.write(target_fingerprint)
|
|
req_dh_params_writer.tgwrite_bytes(cipher_text)
|
|
|
|
req_dh_params_bytes = req_dh_params_writer.get_bytes()
|
|
sender.send(req_dh_params_bytes)
|
|
|
|
# Step 2 response: DH Exchange
|
|
encrypted_answer = None
|
|
with BinaryReader(sender.receive()) as reader:
|
|
response_code = reader.read_int(signed=False)
|
|
|
|
if response_code == 0x79cb045d:
|
|
raise AssertionError('Server DH params fail: TODO')
|
|
|
|
if response_code != 0xd0e8075c:
|
|
raise AssertionError('Invalid response code: {}'.format(
|
|
hex(response_code)))
|
|
|
|
nonce_from_server = reader.read(16)
|
|
if nonce_from_server != nonce:
|
|
raise NotImplementedError('Invalid nonce from server')
|
|
|
|
server_nonce_from_server = reader.read(16)
|
|
if server_nonce_from_server != server_nonce:
|
|
raise NotImplementedError('Invalid server nonce from server')
|
|
|
|
encrypted_answer = reader.tgread_bytes()
|
|
|
|
# Step 3 sending: Complete DH Exchange
|
|
key, iv = utils.generate_key_data_from_nonce(server_nonce, new_nonce)
|
|
plain_text_answer = AES.decrypt_ige(encrypted_answer, key, iv)
|
|
|
|
g, dh_prime, ga, time_offset = None, None, None, None
|
|
with BinaryReader(plain_text_answer) as dh_inner_data_reader:
|
|
dh_inner_data_reader.read(20) # hash sum
|
|
code = dh_inner_data_reader.read_int(signed=False)
|
|
if code != 0xb5890dba:
|
|
raise AssertionError('Invalid DH Inner Data code: {}'.format(code))
|
|
|
|
nonce_from_server1 = dh_inner_data_reader.read(16)
|
|
if nonce_from_server1 != nonce:
|
|
raise AssertionError('Invalid nonce in encrypted answer')
|
|
|
|
server_nonce_from_server1 = dh_inner_data_reader.read(16)
|
|
if server_nonce_from_server1 != server_nonce:
|
|
raise AssertionError('Invalid server nonce in encrypted answer')
|
|
|
|
g = dh_inner_data_reader.read_int()
|
|
dh_prime = get_int(dh_inner_data_reader.tgread_bytes(), signed=False)
|
|
ga = get_int(dh_inner_data_reader.tgread_bytes(), signed=False)
|
|
|
|
server_time = dh_inner_data_reader.read_int()
|
|
time_offset = server_time - int(time.time())
|
|
|
|
b = get_int(os.urandom(2048), signed=False)
|
|
gb = pow(g, b, dh_prime)
|
|
gab = pow(ga, b, dh_prime)
|
|
|
|
# Prepare client DH Inner Data
|
|
with BinaryWriter() as client_dh_inner_data_writer:
|
|
client_dh_inner_data_writer.write_int(
|
|
0x6643b654, signed=False) # Client DH Inner Data
|
|
client_dh_inner_data_writer.write(nonce)
|
|
client_dh_inner_data_writer.write(server_nonce)
|
|
client_dh_inner_data_writer.write_long(0) # TODO retry_id
|
|
client_dh_inner_data_writer.tgwrite_bytes(
|
|
get_byte_array(
|
|
gb, signed=False))
|
|
|
|
with BinaryWriter() as client_dh_inner_data_with_hash_writer:
|
|
client_dh_inner_data_with_hash_writer.write(
|
|
sha1(client_dh_inner_data_writer.get_bytes()).digest())
|
|
|
|
client_dh_inner_data_with_hash_writer.write(
|
|
client_dh_inner_data_writer.get_bytes())
|
|
|
|
client_dh_inner_data_bytes = \
|
|
client_dh_inner_data_with_hash_writer.get_bytes()
|
|
|
|
# Encryption
|
|
client_dh_inner_data_encrypted_bytes = AES.encrypt_ige(
|
|
client_dh_inner_data_bytes, key, iv)
|
|
|
|
# Prepare Set client DH params
|
|
with BinaryWriter() as set_client_dh_params_writer:
|
|
set_client_dh_params_writer.write_int(0xf5045f1f, signed=False)
|
|
set_client_dh_params_writer.write(nonce)
|
|
set_client_dh_params_writer.write(server_nonce)
|
|
set_client_dh_params_writer.tgwrite_bytes(
|
|
client_dh_inner_data_encrypted_bytes)
|
|
|
|
set_client_dh_params_bytes = set_client_dh_params_writer.get_bytes()
|
|
sender.send(set_client_dh_params_bytes)
|
|
|
|
# Step 3 response: Complete DH Exchange
|
|
with BinaryReader(sender.receive()) as reader:
|
|
# Everything read from the server, disconnect now
|
|
sender.disconnect()
|
|
|
|
code = reader.read_int(signed=False)
|
|
if code == 0x3bcbf734: # DH Gen OK
|
|
nonce_from_server = reader.read(16)
|
|
if nonce_from_server != nonce:
|
|
raise NotImplementedError('Invalid nonce from server')
|
|
|
|
server_nonce_from_server = reader.read(16)
|
|
if server_nonce_from_server != server_nonce:
|
|
raise NotImplementedError('Invalid server nonce from server')
|
|
|
|
new_nonce_hash1 = reader.read(16)
|
|
auth_key = AuthKey(get_byte_array(gab, signed=False))
|
|
|
|
new_nonce_hash_calculated = auth_key.calc_new_nonce_hash(new_nonce,
|
|
1)
|
|
if new_nonce_hash1 != new_nonce_hash_calculated:
|
|
raise AssertionError('Invalid new nonce hash')
|
|
|
|
return auth_key, time_offset
|
|
|
|
elif code == 0x46dc1fb9: # DH Gen Retry
|
|
raise NotImplementedError('dh_gen_retry')
|
|
|
|
elif code == 0xa69dae02: # DH Gen Fail
|
|
raise NotImplementedError('dh_gen_fail')
|
|
|
|
else:
|
|
raise AssertionError('DH Gen unknown: {}'.format(hex(code)))
|
|
|
|
|
|
def get_fingerprint_text(fingerprint):
|
|
"""Gets a fingerprint text in 01-23-45-67-89-AB-CD-EF format (no hyphens)"""
|
|
return ''.join(hex(b)[2:].rjust(2, '0').upper() for b in fingerprint)
|
|
|
|
|
|
# The following methods operate in big endian (unlike most of Telegram API) because:
|
|
# > "...pq is a representation of a natural number (in binary *big endian* format)..."
|
|
# > "...current value of dh_prime equals (in *big-endian* byte order)..."
|
|
# Reference: https://core.telegram.org/mtproto/auth_key
|
|
def get_byte_array(integer, signed):
|
|
"""Gets the arbitrary-length byte array corresponding to the given integer"""
|
|
bits = integer.bit_length()
|
|
byte_length = (bits + 8 - 1) // 8 # 8 bits per byte
|
|
return int.to_bytes(
|
|
integer, length=byte_length, byteorder='big', signed=signed)
|
|
|
|
|
|
def get_int(byte_array, signed=True):
|
|
"""Gets the specified integer from its byte array. This should be used by the authenticator,
|
|
who requires the data to be in big endian"""
|
|
return int.from_bytes(byte_array, byteorder='big', signed=signed)
|