A Novel Conditional Access Architecture for TV Service Protection

In broad TV network, the broadcasting will coexist with interactive services in a single set-top-box (STB) device and the traditional unidirectional conditional access system (CAS) in DVB can´t be adapted to the variation. The dual-CAS is designed based on a double layer security scheme proposed in this paper to implement the authentication and access control, key updates between servers and STBs. In the dual-CAS, on the one hand, the layering user agent mechanism is established in STBs to provide transparent streaming security service to upper applications. On the other hand, the dual layer security scheme is designed to protect the ECM transmission, and master key management scheme is used to enhance the security and the system flexibility. In addition, two types of watermark are also involved in the dual-CAS, fingerprint watermark for piracy tracing, legality watermark for conditional playing. Contrast with the traditional DVB CAS, the dual-CAS architecture proposed in this paper is more flexibility and secure.