Cryption and decryption communication semiconductor device and recording/reproducing apparatus

A cryption 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 for performing transmission/reception of a signal 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 circuit which performs encryption and decryption of digital data;
• and
• interfaces each of which enables a connection to a device for recording or reproducing the digital data,
• wherein as the interfaces, at least one first interface enabling a connection to a device for recording or reproducing digital data and at least one second interface enabling a connection to a device for reproducing or recording digital data are respectively provided, and the encryption/decryption circuit is capable of encrypting or decrypting data inputted from the first or second interface and outputting the data to the second or first interface.