Abstract: Most of the Certificateless tripartite Key Agreement（CL-TKA） protocols use the pairings. After analyzing the existing CL-TKA schemes, a novel CL-TKA protocol is proposed based on the certificateless public key cryptography theory. This protocol solves the key escrow problem of the identity-based public key cryptography（ID-PKC）. The analysis has showed that this protocol provides a high security and efficient.

Key words: certificateless, public key cryptography, tripartite key agreement, bilinear pairings

摘要： 对于目前提出的无证书三方密钥协商方案大都使用了耗费时间的对运算，具有较大的计算量，根据离散对数（DL）问题并以公钥密码学理论为基础，设计出一个不用到对运算的无证书三方密钥协商协议，该协议解决了基于身份的密钥协商中的密钥托管的问题。经过安全性证明和效率比较表明该协议有较高的安全性和效率。

关键词: 无证书, 公钥密码体制, 三方密钥协商, 双线性对