Digital Tv Conditional Access System

With the progress of information technology and the improvement of people's standard of living, digital TV (DTV) is stepping into more and more families. DVB standard is the most widely used DTV standard. STB is an important receiving-equipment in the interim from simulative TV to digital TV. And, CA is the essential condition of the development of digital TV. In this paper, the basic concepts of digital TV are introduced firstly. And the infrastructure of DVB standard is the emphasis. Then, we introduce the concepts of CA and it's developing status. The emphasis of our research is the work theory of CAS and the concept of control word (CW), ECM and EMM. Base on these researches, we introduce the ChinaCrypt, a CAS developed by DTVIA, and the work of porting it to STB.