Patent ID: 7218736

Claim:
A method for transferring data on a bus system using both isochronous communication and asynchronous communication; said isochronous communication is for any device on the bus to receive synchronous data; said asynchronous communication is for a predetermined device to receive asynchronous data; said synchronous data capable of containing actual data and encryption identification information indicating encrypted actual data; and encrypted actual data is decrypted using decrypting information obtained through the following steps: a) receiving said synchronous data at a receiving device, said encryption identification information received by said receiving device without encryption, and said receiving device via said asynchronous communication requesting decrypting information for said actual data from a sending device sending said synchronous data, if said encryption identification indicates encrypted actual data; b) receiving said request at said sending device and said sending device sending one of: i) encrypted decrypting information of said actual data; and ii) decrypting information data for obtaining said decrypting information, to said receiving device via said asynchronous communication; and c) executing at said receiving device one of: i) extracting said decrypting information from said encrypted decrypting information; and ii) obtaining said decrypting information using said decrypting information data.