有条件接收系统中基于分级访问控制的密钥分配算法

有条件接收系统通过对节目信息进行加扰从而达到对用户收取收视费用．安全性是衡量有条件接收系统的重要指标，它直接取决于所采用的加扰算法和密钥分配算法．提出一种应用于数字电视广播中有条件接收系统的基于分级访问控制的密钥分配算法．该算法不仅能够大大地降低加密的计算量且能够获得较高的效率和安全性，而且还能够灵活地处理用户的加入与离开，这对于运营商动态管理收视用户有着重要的价值．

Key Distribution Algorithm Based on Hierarchical Access Control for Conditional Access System

Conditional Access System (CAS) is used to charge the subscriber for subscribing fee by scrambling the program information. Security is an essential factor of CAS, which mainly depends on scrambling algorithm and key distribution algorithm. This paper proposed a new key distribution algorithm based on hierarchical access control for conditional access system in digital television broadcast. This key distribution algorithm can greatly reduce the encrypting computation and acquire high efficiency and security. Moreover, the proposed scheme is more flexible in processing joining and leaving of subscriber, which is very important for service provider to dynamic manage the subscriber.