Principle Research And Project Implementation Of DTV Conditional Access System

Pay-TV and data broadcasting are considered to be the future direction and momentum of TV broadcasting networks. But controllable and payable service is the basic qualification to develop pay TV and data broadcasting business. In order to develop TV business well, we must fetch in the condtional access system (CAS), In the other hand, CAS is also an important part of integrated using of digital TV, for example, Video on Demand business, electronics commerce business, Internet connect business also need charge counting and management. So CAS has become to be a research and development hotspot in many academe and companies in TV fields. The thesis mainly studies the basic principle of CAS and its implementation of on DVB-C Set Top Box (STB). The developing history of CAS and its current situation are introduced firstly. Then some CAS related international standards and Chinese national standards are briefly described, and smart card communication protocol , encryption arithmetics like DES and RSA are simply introduced . Then the framework and work mechanism of the CAS are analysed, and the encryption and decryption procedure of CAS are discussed, too. Especially, some key technologies in CAS are describled throuthly, such as the key distribution and management technology, the entitlement control message (ECM) and entitlement management message (EMM) generation and plugging technology, the Application of IC card technology. As the project instance, the thesis introduces the design and implementation of ChinaCrypt's CAS on the DVB-C STB based on the QAMi5516 platform, and detailedly describes each module of the software system, and mentions some difficulties and their settlements in the development. Finally, the thesis gives a comment to the security of the CAS. By the end of this thesis, the author forecasts the future CAS technology will be more flexible, exoteric and securer. Furthermore the thesis describes the rough framework of Removable-Card technology which has received a great attention.