Patent ID: 7290148

Claim:
An encryption and decryption communication semiconductor device, comprising: a link circuit which performs a process based on specs of a LINK layer of an IEEE1394 standard; a communication circuit provided between the link circuit and an external terminal to which a communication medium is connected, and which performs transmission/reception of isochronous data to and from an external device via the communication medium; a packet processing circuit which generates a transmit packet of a predetermined format containing transmit data and extracts received data included in a received packet; an encryption/decryption device which performs encryption and decryption of isochronous data; and a plurality of interfaces, each of which enables a connection to a corresponding external device for recording or reproducing the isochronous data, and which can perform input/output of isochronous data from and to the link circuit via the encryption/decryption device and from and to the corresponding external device; and wherein the plurality of interfaces include a first interface enabling a connection to a device for reproducing isochronous data and a second interface enabling a connection to a device for recording isochronous data, and the encryption/decryption device encrypts data inputted from the first interface and outputs the encrypted data to the second interface, and decrypts data inputted from the second interface and outputs the decrypted data to the first interface.