Conditional access broadcasting. Datacare 2: An over-air enabled system for general purpose data channels

This Report describes an encipherment system, known as Datacare 2, which was originally developed to provide over-air enabled Conditional Access facilities for a Datacast data channel. The key management techniques are based on original proposals for applying Conditional Access facilities to DBS television services but several improvements have been made. In particular, the data protocol for this system allows self-contained operation within a single data channel and permits the complete decoding operation to be performed by a single-chip microprocessor.