A smart-card-based conditional access subsystem separation scheme for digital TV broadcasting

In this paper we present a smart-card-based conditional access subsystem (CASS) separation scheme at the digital TV broadcasting receiving end. Following the proposed scheme, different conditional access (CA) systems can operate concurrently in one digital TV broadcasting network using a common receiving platform, which is independent of any specific CA system. The digital TV program subscriber needs only to change the corresponding CA smart card to view pay TV programs, which are scrambled by different CA systems. The main points of the proposed scheme and its reference implementation are presented in this paper. The reference implementation has been developed to verify the feasibility of the proposed scheme in practical broadcasting environment. The system architecture and the constituent logical function modules of this reference implementation, especially the part in STB, have been described in detail to better illustrate the working principle of this scheme. Compared to PC-card-based or other smart-card-based common interface schemes, the proposed one is much more cost performance efficient, succincter and easier to be accepted by CA system providers. This scheme is also one of the candidate standards for Chinese digital TV broadcasting.