Abstract: Authentication and key exchange functions, such as those conforming to the Digital Transmission Licensing Authority's (DTLA) Digital Transmission Content Protection (5C) Specification, are incorporated into a link-layer access device of a conventional processing system. Because of the suitability of IEEE 1394 for transferring audio/video information, these functions are preferably embodied in an IEEE 1394 compatible link-layer access device. The link-layer access device of this invention is configured to support, for example, the elliptic curve multiplication functions of a Diffie-Hellman key exchange process, as well as digital signature generation and digital signature verification. By incorporating the authentication and key exchange functions into a link-layer access device, the system architecture and devices that are commonly used in conventional processing systems can be used, thereby providing an incremental path toward increased protection of copyright material.