Lai的三方密钥协商协议的密码分析与改进

Cryptanalysis and improvement of Lai's authenticated group key transfer protocol

最近,Lai等人利用加强的Chebyshev混沌映射设计了一个三方密钥协商协议,声称该协议能够抵抗各类攻击。针对Lai协议中存在的匿名传输等方面的缺陷,通过拦截、修改用户与可信第三方之间的传输数据,成功进行了中间人攻击。在Lai等人的协议基础之上,利用哈希函数、加强的Chebyshev混沌映射以及对称加密思想提出了一个改进方案。分析表明,改进协议在保持Lai协议良好性能的基础上,不但保证了信息传输的安全性,而且能够有效抵抗中间人攻击及其他多种攻击。

Recently, Lai et al. first designed a three-party key agreement protocol using enhanced Chebyshev chaotic map, and claimed that the protocol could resist various attacks. To analyze the drawbacks of the protocol in anonymous transmission process, this paper made a man-in-the-middle attack successfully by intercepting and modifying the transmitted data between the user and the trusted third party. Then it constructed a new improved protocol adopting hash function, enhanced Chebyshev chaotic map and symmetric encryption method based on Lai et al. ＇ s protocol. Analysis demonstrates that the proposal protocol holds the good properties of Lai et al. ＇ s protocol. It not only can ensure the security of information transmission, but also can resist man-in-the-middle attack and other attacks effectively.