def get_client_key_exchange_record(cls, robot_payload_enum, tls_version, modulus, exponent):
"""A client key exchange record with a hardcoded pre_master_secret, and a valid or invalid padding.
"""
# type: (RobotPmsPaddingPayloadEnum, TlsVersionEnum, int, int) -> TlsRsaClientKeyExchangeRecord
pms_padding = cls._compute_pms_padding(modulus)
tls_version_hex = binascii.b2a_hex(TlsRecordTlsVersionBytes[tls_version.name].value).decode('ascii')
pms_with_padding_payload = cls._CKE_PAYLOADS_HEX[robot_payload_enum]
final_pms = pms_with_padding_payload.format(pms_padding=pms_padding, tls_version=tls_version_hex,
pms=cls._PMS_HEX)
cke_robot_record = TlsRsaClientKeyExchangeRecord.from_parameters(
tls_version, exponent, modulus, int(final_pms, 16)
)
return cke_robot_record
def test_rsa_client_key_exchange_to_bytes(self):
# Inspired by https://github.com/robotattackorg/robot-detect
modulus = int(self.MODULUS_HEX, 16)
exponent = int(self.EXPONENT_HEX, 16)
modulus_bit_size = int(math.ceil(math.log(modulus, 2)))
modulus_byte_size = (modulus_bit_size + 7) // 8
pre_master_secret = "aa112233445566778899112233445566778899112233445566778899112233445566778899112233445566778899"
# Generate padding - it should be of the form "00 02 <random> 00 <TLS version> <premaster secret>
tls_version_hex = binascii.b2a_hex(TlsRecordTlsVersionBytes[
TlsVersionEnum.TLSV1_2.name].value).decode('ascii')
pad_len = (modulus_byte_size - 48 - 3) * 2
rnd_pad = ("abcd" * (pad_len // 2 + 1))[:pad_len]
pms_with_padding = int(
"0002" + rnd_pad + "00" + tls_version_hex + pre_master_secret, 16)
record = TlsRsaClientKeyExchangeRecord.from_parameters(
TlsVersionEnum.TLSV1_2, exponent, modulus, pms_with_padding)
self.assertEqual(record.to_bytes(),
self.EXPECTED_CLIENT_KEY_EXCHANGE_BYTES)