Principle And Impletation Of Digital TV Conditional Access

With the development of the digital television, many new services have been provided to serve people, such as Video-On-Demand, pay-per-view, information-on-demand. Digital television provided a service platform for services and Network Company. The conditional access is the key system of the digital television. It ensures the benefit of consumer, program supply and network company. It guarantees the legal benefit of consumer and supply by encryption technology, good design and strict rule of law.This paper is based on the concise and deep-going survey of CA system and finished the following three parts:1. Introduce the encryption technology involved in the CA system; analyze the principle and the secure framework of the CA system, including the composition, principle, architecture and secure framework of the CA system.2. Introduce the concept of IP-CA, suggest to design the CA system based on IP net, the design not only scrambles the original video stream according to the standard scrambler, but also uses the security authentication system, instead of the IC card, to realize the authentication, authorization and charge management.3. Describe the design of the CA system based on IP net, and the Identity Authentication system uses the digital certificate to realize the Authentication of client's identity, and Secure Tunnel system uses the Digital Signature, Asymmetrical Encryption and Digital Envelope Technology to ensure the confidentiality and integrality of the communication between the server and client. At last, describe the architecture and function of the client which belongs to the IP-CA system.The IP-CA system takes take advantage of the duplex communication in the IP net, and uses the software to replace the IC card, then not only reduces the cost of the system and enhances the security of the system, but also provides one method for the convergence of cable net and IP net.