Patent ID: 8130691

Claim:
A relay apparatus comprising: a communication network interface that receives, via a communication network, an IP packet from a source terminal; a broadcast wave interface for transmitting the IP packet, received via the communication network interface, to a destination terminal via a digital broadcast wave over a broadcast network, said communication network and said broadcast network are two different networks; and a routing processing unit that broadcasts, from the broadcast wave interface, the IP packet received from the source terminal via the communication network, to the destination terminal, wherein the relay apparatus is configured to establish at least one path via said communication network interface and another path via said broadcast wave interface so that a bidirectional communication between the source terminal and the destination terminal is performed via said one path and another path in a real time, and wherein the relay apparatus is configured to send a first key to each of the source terminal and the destination terminal via the communication network and a second key to each of the source terminal and the destination terminal via the broadcast network, said second key is encrypted by the first key, and wherein the first key of the source terminal is different from the first key of the destination terminal and the second key of the source terminal is same as the second key of the destination terminal, said second key is valid only for one communication.