Abstract: Active Network is a new model network，and it has applied in some fields.The Demand Loading Code Protocol is based on mobile code，demand loading，and cache techniques that allow new protocols and service to be dynamically deployed.Because of the Demand Loading Code Protocol exist replay attack，letdown the performance and efficiency of network，so this paper presents a new effective protocol based on hash function，active node needn’t decryptions the packet to detect the replay attacker，and enhance the capacity for replay attack.Its security and computational overhead are analyzed in detail.

摘要： 主动网络是一种新型的网络，在一些领域已得到初步应用。主动网络中的需求装载代码协议是基于移动代码，装载需求和缓存技术的代码分配协议，可动态配置新的协议和服务。由于已有需求装载代码协议存在被重放的安全缺陷，影响主动节点的性能和效率，为此提出了一个安全有效的改进协议，利用Hash函数的单向性，协议双方无需对报文解密就可判断重放攻击，增强了其抵抗重放攻击的能力，并进行了安全性和计算复杂度分析。