code: def set_inbound_cipher(
          self, block_engine, block_size, mac_engine, mac_size, mac_key
      ):
          
          self.__block_engine_in = block_engine
          self.__block_size_in = block_size
          self.__mac_engine_in = mac_engine
          self.__mac_size_in = mac_size
          self.__mac_key_in = mac_key
          self.__received_bytes = 0
          self.__received_packets = 0
          self.__received_bytes_overflow = 0
          self.__received_packets_overflow = 0
          # wait until the reset happens in both directions before clearing
          # rekey flag
          self.__init_count |= 2
          if self.__init_count == 3:
              self.__init_count = 0
              self.__need_rekey = False
docs: Switch inbound data cipher.