Abstract: The security of existing tripartite authenticated key agreement protocol is poor, and the computing costs of that are high. An identity-based enhanced tripartite authenticated key agreement protocol is proposed. The new protocol achieves the basic security properties, and uses the short signature and time stamp to further enhance security. Analysis shows that the enhanced protocol meets the known security properties of tripartite key agreement, and has only two bilinear pairing operations. Its computing costs are lower than other ones. In addition, this paper proposes stronger key-compromise impersonation resilience. For the first time, the serious faults of the schemes of Chen Hao and Chen Jiaqi et al are pointed out.

Key words: identity-based cryptography, tripartite authenticated, key agreement, bilinear pairing

摘要： 现有的三方认证密钥协商协议安全性低且计算开销较大，提出一种基于身份的增强三方认证密钥协商协议。新协议在实现密钥协商基本安全属性的同时，利用短签名和时间戳技术进一步提高安全性。分析表明，增强协议能满足现有已知的三方密钥协商安全属性，且仅需两次双线性对运算，计算开销更低。此外，提出更强的抗密钥泄露伪装属性，首次指出陈浩等人以及陈家琪等人方案存在重大缺陷。

关键词: 基于身份密码, 三方认证, 密钥协商, 双线性映射