基于DVB的CA系统的工作机理

Operational Principle of CA System Based on DVB

基于DVB的CA系统通过同密/多密等技术构建。在发送端以控制字产生伪随机序列,用公共加扰算法对音视频节目数据流加扰,并通过IDEA算法对加扰所用的控制字加密。在接收端用事先获得的已加密控制字解密并恢复原控制字,然后对收到节目信息解扰出正常节目。

The CA system based on DVB was set up by same-encrypt/multi-encrypt technology etc. The false random serial was produced by control word, the data bit-stream of program signal was scrambled by common scrambling algorithm, and also the scrambled control word was encrypted by IDEA algorithm at sending end in DVB. The encrypted control word acquired in advance was decrypted to recover normal control word by relevant decrypting algorithm, and then, the scrambled program information was descrambled to recover normal program information at receiving end.