def build_extended_cell(y, gy, streamID: int, circ_id: int, gx: str, recognized) -> Cell:
"""
The method to build the extended Cell object
:param y:
:param gy:
:param streamID:
:param circ_id:
:param gx:
:param recognized:
:return: The Extended Cell
"""
gxy = CoreCryptoDH.compute_dh_shared_key(y, gx)
kdf_dict = CoreCryptoRSA.kdf_tor(gxy)
server_h_data = TapSHData(gy, kdf_dict['KH'])
# Construct extended2 payload
extended_cell_payload_relay = RelayExtendedPayload(RelayExtendedPayload.TAP_S_HANDSHAKE_LEN, server_h_data)
# Calculate digest from the extended2 payload
payload_dict = {
'HLEN': extended_cell_payload_relay.HLEN,
'HDATA': extended_cell_payload_relay.HDATA
}
digest = CoreCryptoMisc.calculate_digest(payload_dict)
# Construct the Relay cell with extended2 payload which is the payload for the Cell class
extended_cell_payload = RelayCellPayload(RelayCellPayload.RELAY_CMD_ENUM['EXTENDED2'], recognized, streamID,
digest, Cell.PAYLOAD_LEN - 11, extended_cell_payload_relay)
# Construct the actual cell
extended_cell = Cell(circ_id, Cell.CMD_ENUM['RELAY'], Cell.PAYLOAD_LEN, extended_cell_payload)
return extended_cell
def parse_encoded_extended_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 = '=H' part_tuple1 = unpack(part_fmt_str1, relay_cell_payload_tuple[5][0:2]) fmt_str = '=H' + str(part_tuple1[0]) + 's' relay_extended_payload_tuple = unpack(fmt_str, relay_cell_payload_tuple[5][0:2+part_tuple1[0]]) h_data_fmt_str = '='+str(CC.DH_LEN)+'s'+str(CC.HASH_LEN)+'s' h_data_tuple = unpack(h_data_fmt_str, relay_extended_payload_tuple[1]) server_h_data = TapSHData(h_data_tuple[0], h_data_tuple[1]) relay_extended_payload = RelayExtendedPayload(relay_extended_payload_tuple[0], server_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_extended_payload) extended_cell = Cell(cell_tuple[0], cell_tuple[1], cell_tuple[2], relay_cell_payload) return extended_cell
def build_created_cell(y_bytes: bytes, gy_bytes: bytes, circ_id: int, gx_bytes: bytes) -> Cell: """ The method used to build a created/created2 cell object :param y_bytes: The diffie hellman private key bytes of the receiver :param gy_bytes: The diffie hellman public key bytes of the receiver :param circ_id: The circuit ID :param gx_bytes: The diffie hellman public key bytes of the sender :return: The created Cell object """ gxy = CoreCryptoDH.compute_dh_shared_key(gx_bytes, y_bytes) kdf_dict = CoreCryptoRSA.kdf_tor(gxy) server_h_data = TapSHData(gy_bytes, kdf_dict['KH']) created_cell_payload = CreatedCellPayload(CreatedCellPayload.TAP_S_HANDSHAKE_LEN, server_h_data) created_cell = Cell(circ_id, Cell.CMD_ENUM['CREATED2'], Cell.PAYLOAD_LEN, created_cell_payload) return created_cell
def parse_encoded_created_cell(cell_bytes: bytes) -> Cell: cell_tuple = Parser.parse_basic_cell(cell_bytes) hlen = CreatedCellPayload.TAP_S_HANDSHAKE_LEN payload_fmt_str = '=H'+str(hlen)+'s' created_cell_payload_tuple = unpack(payload_fmt_str, cell_tuple[3][0:(2+hlen)]) h_data_fmt_str = '='+str(CC.DH_LEN)+'s'+str(CC.HASH_LEN)+'s' h_data_tuple = unpack(h_data_fmt_str, created_cell_payload_tuple[1]) server_h_data = TapSHData(h_data_tuple[0], h_data_tuple[1]) created_cell_payload = CreatedCellPayload(created_cell_payload_tuple[0], server_h_data) created_cell = Cell(cell_tuple[0], cell_tuple[1], cell_tuple[2], created_cell_payload) return created_cell