Patent ID: 7472415

Claim:
A digital signal receiver apparatus comprising: a digital signal bus input/output circuit which connects to a digital signal bus and transmits or receives a digital signal to or from external digital signal transmitter apparatuses connected to said digital signal bus; a controller which generates instructions to said external digital signal transmitter apparatuses and executes instructions from said external digital signal transmitter apparatuses; a decryptor which decrypts a signal from said external digital signal transmitter apparatuses; a packet processing circuit which converts an instruction from said controller to a transmission packet, and converts a received packet from said external digital signal transmitter apparatuses to an instruction to said controller, and converts a received packet from said external digital signal transmitter apparatuses to a digital signal to said decryptor; and a bus control circuit which transmits said transmission packet to said digital signal bus and receives said received packet from said digital signal bus via said digital signal bus input/output circuit; wherein said controller requests an authentication at a predetermined timing by generating an instruction for authentication request and performs the authentication to said external digital signal transmitter apparatuses and shares key information by exchanging said instructions with said transmission packets and received packets, and said decryptor decrypts said digital signal on the basis of said key information.