A scheme for realizing a contents protection procedure between devices that are not connected to the same network, in a system where the IEEE 1394 buses are connected together through a 1394 bridge or a system where the IEEE 1394 buses are connected together through another radio network, is disclosed. A network connection device notifies information regarding a transmission node on the first IEEE 1394 bus to a reception node on the second IEEE 1394 bus, so that the reception node can carry out the authentication and key exchange procedure directly with the transmission node on a different network.