Hierarchical Key Distribution Scheme for Conditional Access System in DTV Broadcasting

A variety of subscriptions in Conditional Access System (CAS) of DTV broadcasting network bring complexity to the key distribution scheme. In this paper, an innovation of hierarchical key distribution scheme for CAS in DTV broadcasting is proposed to reduce the computation of encryption and the number of messages for key refreshment. Compared with the conventional key distribution schemes, no encrypted message is distributed for key refreshment when a subscriber leaves. Further more, our hierarchical tree of key can provide a lot more dynamic management, from which broadcasters can improve efficiency in managing program channels.