Abstract: A key exchange protocol is designed to allow entities establishing a session key to encrypt data over an open network.This paper presents an identity-based tripartite key exchange protocol from Weil pairing.The protocol provides the desired security attributes of an authenticated key exchange protocol.Compared with the previously proposed protocols，it reduces the computational cost.

摘要： 密钥协商协议是在公开的信道上，两个或多个参与方之间共享密钥的机制。设计了一个利用Weil配对的基于身份的三方密钥交换协议，协议能完全满足密钥交换协议要求的安全特性，且具有更高的效率。