密钥管理系统是安全组播的重要组成部分,而用户密钥存储量和密钥更新代价又是衡量密钥管理系统性能的关键因素.一个高性能的密钥管理系统应具有较小的用户密钥存储量和密钥更新代价.利用信源编码理论深入研究了基于用户概率模型的密钥管理问题,证明了采用密钥Huffman层次结构的密钥管理系统的平均密钥更新代价和用户密钥存储量最小,同时还推导得出了密钥层次结构的理论平均密钥更新代价和用户密钥存储量的下限.

Key management system is an important part of secure multicast, while the number of keys held by each user and the cost of re-keying are crucial factors which closely related to the performance of key management system. The key management system with less number of keys held by each user and less cost of re-keying is efficient. In this paper, the key management problem is investigated based on the user probability model by using the source coding theory. And it is proved that in the key management system using Huffman hierarchy, the average cost of re-keying and the number of keys held by each user are minimal. Meanwhile, the lower bounds of the average cost of re-keying and the number of keys held by each user in theory are provided.

(Supported by the Assisting Project of Ministry of Education of China for Backbone Teachers of University and College under Grant No.2992 (国家教育部高等院校骨干教师资助计划)