基于重路由匿名通信系统的负载分析

基于重路由匿名通信系统,如Mixes,Onion Routing,Crowds等,采用重路由机制在应用层转发数据,使实体之间的通信以间接的方式进行,从而有效地隐藏通信实体的身份信息,如主机的IP地址等.在性能方面,这种机制导致系统中产生额外的开销,如通信延时、负载等.着重从理论上分析了系统中的成员负载.通过深入考查基于重路由匿名通信系统的重路由机制,推导出了基于重路由匿名通信系统中成员负载的概率公式,证明了成员负载由系统中成员数目重路由路径数目以及重路由路径长度的概率分布所决定.应用该公式计算Crowds系统中成员的负载,得出精确的负载期望值为1/(1(P_f)+1,改进了Reiter等人的分析结果O((n+1)/((1(P_f)²n), 证明了Crowds系统的成员负载不受系统中成员数目n的影响,具有良好的可伸缩性.并通过仿真实验验证了该分析结果.其结论为设计和规划匿名网络提供了理论依据.

Payload Analysis of Rerouting-Based Anonymous Communication Systems

Rerouting mechanism is adopted by rerouting-based anonymous communication systems such as Mixes, Onion Routing, and Crowds, to store and forward data in application layer. With this, users can communicate in an indirect way. Thus, identity information such as IP addresses can be effectively hidden against eavesdropper. This mechanism, however, can result in extra overhead in performance such as communication delay and participant payload, which may affect the applications of anonymous communication systems. In this paper, the participant payload induced by the rerouting mechanism is studied quantitatively. By investigating the establishment of rerouting paths in detail, a probability formula for calculating the participant payload is derived, which proves that the participant payload is determined by the number of participants, the number of rerouting paths, and the probability distribution of length of the rerouting paths. By applying this formula to a practical anonymous communication system, Crowds, a precise expected participant payload 1/(1-P_f)+1 can be derived, which significantly improves Reiter and Rubin's original analysis O((n+1)/((1(P_f)²n), and demonstrates that the participant payload in Crowds remains constant and is independent of the variation of the number of participants in Crowds. Simulation results are presented to testify the theoretical analysis. The conclusions can provide a theoretical support for the design and implementation of anonymous communication systems.