Abstract: The integration of P2P and SIP is widely used in multimedia communication，which can resolve the problem of single-point failure in traditional SIP based network.Nevertheless，lots of security problems appear because of the lack of effective authentication.Most present P2P-SIP system authentications try to adopt peers’ real ID，which can not meet the demand of anonymity of peers.In this paper，an anonymous authentication policy named as DHB based on Diffie-Hellman algorithm is proposed to cope with this problem.At the initialization stage of algorithm，DHB uses PIAC to generate peers’ pseudonymous name.At the authentication stage，peers’ shared information and improved Diffie-Hellman algorithm are used to make certification between peers.The theoretical and experimental analysis shows that DHB is safe and effective，which can resist man-in-middle attack and key guessing attack.

Key words: Session Initiation Protocol（SIP）, security communications, anonymity, authentication

摘要： P2P和SIP融合技术已经普遍应用于多媒体通信中，它解决了传统的SIP网络单点失效的问题。但是由于现有的P2P-SIP缺少有效的认证方案，给其带来很多安全隐患。现有的P2P-SIP网络的认证方案大多采用节点的真实ID，不能满足其匿名性的特殊要求。针对这个问题，提出了一种基于Diffie-Hellman算法的节点匿名认证方案DHB，该方案初始化阶段使用代理ID分发中心PIAC产生节点的假名。认证阶段采用改进的Diffie-Hellman算法和节点共享信息进行身份认证，实现了P2P-SIP中节点间的匿名认证。理论和实验分析表明，DHB可以有效抵御中间人攻击和猜测攻击，是一种安全有效的节点匿名认证方案。

关键词: 会话初始化协议, 通信安全, 匿名, 认证