文中分析了VoIP系统存在的安全问题和CPK技术的工作原理,对CPK认证技术与其他认证技术进行了比较,将基于标识的组合公钥体制CPK应用到VoIP系统中。介绍了安全VoIP系统的组成,阐述了终端之间的认证流程和会话密钥生成方式,认证过程中设备公私钥均不暴露在外,实现认证的同时完成密钥生成,以很小的网络开销提高了VoIP系统的安全性。 In this paper, the security problems existing in VoIP system and the working principle of CPK technology are analyzed. CPK authentication technology is compared with other authentication technologies, and the CPK, which is based on identity, is applied to VoIP system. The composition of a secure VoIP system is introduced. The process of authentication and the generation of session keys are described. During the authentication process, both the public and private keys of the device are not exposed, and the key generation is completed simultaneously with authentication. With a small network overhead VoIP system security.