中文摘要：

安全协议在维护网络安全的过程中,都需要采用密码算法来达到其安全的目的.在其运行的初始阶段,要进行复杂计算,并需保存相关状态信息,这使得其存在拒绝服务攻击的安全隐患.本文分析针对安全协议的拒绝服务攻击方式,并重点讨论防御攻击的puzzle方法,定量的研究其防御拒绝服务攻击的过程,给出了难度系数的调整公式,进一步提出请求成功率保证算法,能根据需要动态调整防御拒绝服务攻击的强度,进而提高安全协议的安全性和系统的运行效率.

英文摘要：

In the process of the maintenance of the network security,security protocol must use cryptographic algorithms to achieve the security.In the initial phase of the security protocol,it has to do the complex computation and to store the correlation behavior information.For this reason,security protocol is vulnerable to denial of service attack.This paper analyzes the process about denial of service attack in the security protocol and is concentrated on the way of the puzzle which is to defend the attack.The quantitative study is on the defense process of the puzzle.The adjustment formula about coefficient of difficulty is given,and then the guarantee algorithm of request success rate is able to dynamically adjust the defense intensity.In order to enhance the security of the security protocol and increase the system＇s operating efficiency.