def hybrid_encrypt(message: bytes, pk: rsa.RSAPublicKey) -> TapCHData:
"""
This method is the hybrid encrypt outlined in the Tor spec 0.4 section
:param message: The message to be encrypted
:param pk: The RSA public to encrypt the message with
:return: The object TapCHData that has the client handshake data
"""
# First convert the message to a byte array so that we can slice it etc.
message = bytearray(message)
if len(message
) <= CryptoConstants.PK_ENC_LEN - CryptoConstants.PK_PAD_LEN:
# Then encrypt the message using the onion key
p = pk.encrypt(
message,
padding.OAEP(mgf=padding.MGF1(algorithm=hashes.SHA256()),
algorithm=hashes.SHA256(),
label=None))
# Create the TAP_H_DATA object
padding_bytes = bytes(CryptoConstants.PK_PAD_LEN)
tap_h_data = TapCHData(padding_bytes, None, p, None)
else:
k = bytearray(os.urandom(CryptoConstants.KEY_LEN))
m1 = message[0:CryptoConstants.PK_ENC_LEN -
CryptoConstants.PK_PAD_LEN - CryptoConstants.KEY_LEN]
m2 = message[CryptoConstants.PK_ENC_LEN -
CryptoConstants.PK_PAD_LEN - CryptoConstants.KEY_LEN:]
p1 = pk.encrypt(
bytes(k + m1),
padding.OAEP(mgf=padding.MGF1(algorithm=hashes.SHA1()),
algorithm=hashes.SHA1(),
label=None))
nonce = bytes(
CryptoConstants.KEY_LEN) # all bytes are 0, nonce is the IV
cipher = Cipher(algorithms.AES(k),
modes.CTR(nonce),
backend=default_backend())
encryptor = cipher.encryptor()
p2 = encryptor.update(m2) + encryptor.finalize()
print(p1, len(p1))
print(p2, len(p2))
print(m2, len(m2))
# tap_h_data = TapCHData(bytearray(p1)[CryptoConstants.PK_ENC_LEN - CryptoConstants.PK_PAD_LEN:],
# bytearray(p1)[0:CryptoConstants.KEY_LEN],
# bytearray(p1)[CryptoConstants.KEY_LEN:(CryptoConstants.PK_ENC_LEN - CryptoConstants.PK_PAD_LEN)],
# p2)
tap_h_data = TapCHData(
bytearray(p1)[0:CryptoConstants.PK_PAD_LEN],
bytearray(p1)[CryptoConstants.PK_PAD_LEN:(
CryptoConstants.PK_PAD_LEN + CryptoConstants.KEY_LEN)],
bytearray(p1)[(CryptoConstants.PK_PAD_LEN +
CryptoConstants.KEY_LEN):], p2)
return tap_h_data
def parse_encoded_create_cell(cell_bytes: bytes) -> Cell: cell_tuple = Parser.parse_basic_cell(cell_bytes) hlen = CreateCellPayload.CREATE_HANDSHAKE_LEN['TAP'] payload_fmt_str = '=HH'+str(hlen)+'s' create_cell_payload_tuple = unpack(payload_fmt_str, cell_tuple[3][0:(2+2+hlen)]) h_data_fmt_str = '='+str(CC.PK_PAD_LEN)+'s'+str(CC.KEY_LEN)+'s'+str(CC.PK_ENC_LEN - CC.PK_PAD_LEN - CC.KEY_LEN)+'s'+str(CC.DH_LEN-(CC.PK_ENC_LEN-CC.PK_PAD_LEN-CC.KEY_LEN))+'s' h_data_tuple = unpack(h_data_fmt_str, create_cell_payload_tuple[2]) h_data = TapCHData(h_data_tuple[0], h_data_tuple[1], h_data_tuple[2], h_data_tuple[3]) create_cell_payload = CreateCellPayload(create_cell_payload_tuple[0], create_cell_payload_tuple[1], h_data) create_cell = Cell(cell_tuple[0], cell_tuple[1], cell_tuple[2], create_cell_payload) return create_cell
def parse_encoded_extend_cell(cell_bytes: bytes) -> Cell:
cell_tuple = Parser.parse_basic_cell(cell_bytes)
relay_cell_payload_tuple = Parser.parse_encoded_relay_cell(cell_bytes)
part_fmt_str1 = '=BBB'
part_tuple1 = unpack(part_fmt_str1, relay_cell_payload_tuple[5][0:3])
part_fmt_str2 = '=BBB' + str(part_tuple1[2]) + 's' + 'HH'
part_tuple2 = unpack(
part_fmt_str2,
relay_cell_payload_tuple[5][0:(3 + part_tuple1[2] + 2 + 2)])
fmt_str = '=BBB' + str(part_tuple1[2]) + 's' + 'HH' + str(
part_tuple2[5]) + 's'
relay_extend_payload_tuple = unpack(
fmt_str, relay_cell_payload_tuple[5][0:(3 + part_tuple1[2] + 2 +
2 + part_tuple2[5])])
h_data_fmt_str = '=' + str(CC.PK_PAD_LEN) + 's' + str(
CC.KEY_LEN) + 's' + str(
CC.PK_ENC_LEN - CC.PK_PAD_LEN - CC.KEY_LEN) + 's' + str(
CC.DH_LEN -
(CC.PK_ENC_LEN - CC.PK_PAD_LEN - CC.KEY_LEN)) + 's'
h_data_tuple = unpack(h_data_fmt_str, relay_extend_payload_tuple[6])
h_data = TapCHData(h_data_tuple[0], h_data_tuple[1], h_data_tuple[2],
h_data_tuple[3])
relay_extend_payload = RelayExtendPayload(
relay_extend_payload_tuple[0], relay_extend_payload_tuple[1],
relay_extend_payload_tuple[2], relay_extend_payload_tuple[3],
relay_extend_payload_tuple[4], relay_extend_payload_tuple[5],
h_data)
relay_cell_payload = RelayCellPayload(relay_cell_payload_tuple[0],
relay_cell_payload_tuple[1],
relay_cell_payload_tuple[2],
relay_cell_payload_tuple[3],
relay_cell_payload_tuple[4],
relay_extend_payload)
extend_cell = Cell(cell_tuple[0], cell_tuple[1], cell_tuple[2],
relay_cell_payload)
return extend_cell