Abstract: Because rerouting routes of groups-based anonymous communication protocol allows the existence of ring，which will increase the appearance probability of sending proxy node on the rerouting routes and affect the anonymity of the system.In this paper，groups-based non-ring definite route length anonymous communication protocol has been proposed to prohibit the appearance of ring on the rerouting routes，restrict the length of the routes.Through theory analysis and simulate test data，it has been certified that the protocol can improve the anonymous performance of the system，reinforce information leakage resistance of the system，control the maximum length of the routes less than the number of the groups and realize receiver anonymity.

Key words: anonymous communication, non-ring definite route length, anonymous performance

摘要： 基于组群匿名通信协议的重路由路径允许存在环，会增加发送代理节点在重路由路径上出现的概率，从而影响系统的匿名度。论文提出基于组群的无环有限路长匿名通信协议，禁止出现环和限制路径长度。通过理论分析和模拟测试数据表明该协议能有效地提高系统的匿名性能，增强系统的抗泄密性，控制路径最长不超过组内成员数，能够实现接收者匿名。

关键词: 匿名通信, 无环有限路长, 匿名性能