def encrypt(self, data, offset=None, length=None):
"""Encrypts the given data with the current key"""
if offset is None:
offset = 0
if length is None:
length = len(data)
with BinaryWriter() as writer:
# Write SHA
writer.write(utils.sha1(data[offset:offset + length]))
# Write data
writer.write(data[offset:offset + length])
# Add padding if required
if length < 235:
writer.write(os.urandom(235 - length))
result = int.from_bytes(writer.get_bytes(), byteorder='big')
result = pow(result, self.e, self.m)
# If the result byte count is less than 256, since the byte order is big,
# the non-used bytes on the left will be 0 and act as padding,
# without need of any additional checks
return int.to_bytes(result,
length=256,
byteorder='big',
signed=False)
def __init__(self, data):
self.key = data
with BinaryReader(utils.sha1(self.key)) as reader:
self.aux_hash = reader.read_long(signed=False)
reader.read(4)
self.key_id = reader.read_long(signed=False)
def test_sha1():
string = 'Example string'
hashsum = utils.sha1(string.encode('utf-8'))
expected = b'\nT\x92|\x8d\x06:)\x99\x04\x8e\xf8j?\xc4\x8e\xd3}m9'
assert hashsum == expected, 'Invalid sha1 hashsum representation (should be {}, but is {})'\
.format(expected, hashsum)
def do_authentication(transport):
"""Executes the authentication process with the Telegram servers.
If no error is rose, returns both the authorization key and the time offset"""
sender = MtProtoPlainSender(transport)
# 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 = Factorizator.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_nonces(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) # hashsum
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(
utils.sha1(client_dh_inner_data_writer.get_bytes()))
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:
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)))