匿名通信中短距离优先分组重路由方法的研究

Research on a Short Distance-Prior Rerouting Scheme in Anonymous Communication

重路由技术是匿名通信系统中采用的主要技术手段之一.目前典型的匿名系统中大多采用随机重路由的策略,即在所有中转代理中随机选择一个进行转发的策略,随机转发策略要求每个中转代理知道系统中所有其他代理.随着系统的扩大,一方面中转代理数增加使得系统维护代价增加,另一方面由于部分中转代理之间距离很远,重路由带来的延迟增加.提出了一种新的重路由策略——距离优先分组重路由,实现了短距离优先转发的策略,重路由时在近距离分组中进行随机转发.分别将距离优先分组策略应用在随机概率转发和有限路长限制的重路由算法中,数学分析和模拟测试结果表明,新的重路由策略在一定分组成员数情况下能保持与非分组重路由算法相当的匿名性能,同时明显地降低了服务延迟.新的策略中每个中转代理只需知道就近分组中的代理,这为匿名系统的扩展性研究提供了一定的基础.

Rerouting is one of the main schemes used in anonymous communication systems. In some typical anonymous communication systems, data packets pass through a numbers of proxies, and then to the end receiver. So the real initiator could be concealed. However, most rerouting schemes used in some prototype systems are random schemes, which choose the forward proxy randomly among all the proxies in a system. Random rerouting scheme requires every proxy to know some information of all the proxies in the system. With systems expanding, the number of proxies in the system increases, which makes the cost for management higher. Furthermore, its expanding will increase the delay of rerouting as the distance between some of the proxies increases. The paper proposes a new rerouting scheme-short distance-prior rerouting, which implements short distance-prior forwarding, and every proxy chooses a forwarder in its nearby group. The new scheme is applied in the random probability forward rerouting and definite path length rerouting algorithms. Mathematic analysis and simulation results indicate that the new scheme can keep almost the same anonymity as the typical ones and can obviously decrease the delay of forwarding. In the new scheme, each proxy only needs to know the information of proxies in its nearby group, which also gives some support to the research of scalability of anonymous systems.