有条件接收系统中基于频道分级的密钥分配算法

安全性是条件接收系统的一个重要指标，而密钥分配是条件接收系统的核心部分，它与安全性直接相关联，考虑到当前有条件接收系统的不足之处，提出了一种基于频道分级的密钥分配算法。其中，分级访问控制技术被用来分配频道的授权密钥，而中国剩余定理被用来为用户分配组密钥。通过分析比较，该算法足够安全，同时能够大大地降低前向安全性问题和保证系统的公平性；能够灵活实现对用户的动态管理。尤其重要的是，相比于当前的有条件接收系统，该算法只需要传递很少的消息就能实现密钥分配，且能大大地节省信道带宽。

The Key Distribution Algorithm Based on Hierarchical Channel for Conditional Access System

The security is one of the most important factors for conditional access system (CAS). Key distribution is the essential part of CAS which is directly related with the security of CAS. Considering the inefficiency of the current CAS, a novel key distribution algorithm based on hierarchical channel was put forward, in which hierarchical access control technology is used to distribute the authorization keys of channels while Chinese remainder theorem is adopted to distribute group keys to subscribers. With analyzing and comparing, the proposed algorithm is secure enough as well as reducing the forward security problem greatly and keeping the fairness. Moreover, the algorithm is flexible in the dynamic management of subscriber. Most importantly, the algorithm needs fewer messages transferred in the process of key distributing than the current CAS, which saves the bandwidth of channel greatly.