when Mode::SERVER
        mac_algorithm_c_to_s_name = @remote_mac_algorithms_client_to_server.find{ |a| @local_mac_algorithms_client_to_server.include? a } or raise
        mac_algorithm_s_to_c_name = @remote_mac_algorithms_server_to_client.find{ |a| @local_mac_algorithms_server_to_client.include? a } or raise
        incoming_mac_algorithm_name = mac_algorithm_c_to_s_name
        outgoing_mac_algorithm_name = mac_algorithm_s_to_c_name