On key distribution management for conditional access system on pay-TV system

A conditional access system (CAS) is essential in a pay-TV system to charge the subscriber the subscription fee, and key management is also important. Various levels of key hierarchy for a CAS are discussed and two methods of grouping the subscribers to reduce the complexity of key distributions are presented. Based on the proposed two grouping methods we proposed a simple and a complete scheme with four-levels of key hierarchy for the key distribution management CAS of the pay-TV system. We also analyze the performance of the proposed complete scheme. It is shown that our system is efficient and suitable for a pay-TV system which provides both pay per channel (PPC) and pay per view (PPV) services. Besides, the proposed complete scheme is also a flexible one for dynamic management. Finally, it should be noted that, though our discussion are focused on pay-TV only, our schemes are also suitable for a digital broadcasting system (DBS)