Study On Attack Models In Anonymous Communication System Based On Rerouting

Along with the enhancement to the network security request in some special departments such as military department, the national defense, and the government divisions, in addition to the enhancement of network privacy request, the research on anonymous communication is getting more and more important. At present, all safety defense technologies focus on attack, but few studies concern about attack model in anonymous communication, therefore, it is essential to enhance this kind of studies.This thesis firstly analyzes and studies a general model of anonymous system based on the P2P- structure rerouting, then proposes two kinds of new attack models: The first attack model is that,the sender transmits data via the fixed rerouting path, the attacker observes multitudinously, carries on the collected operation to active node in the system, and thus finds out the sender. The theoretical analysis and the analog computation indicate that the probability of finding out the sender in this model is 1 when the system scale, the rerouting length or the observation frequencies achieve certain value. and the system anonymity is destructed. The other is based on transmission strategy with the fixed length and changable rerouting path. It observes the system multitudinously with the help of several other attackers. The theoretical analysis and the analog computation indicate that the probability of the attacker's finding out the sender increases according to the observation frequencies and the increasing number of other attackers and it thus satisfies the intention of destructing the sender's data anonymously. This thesis proposes one kind of transmission strategy by changing path and length and the improved system model on rerouting in order to expire the above two kinds of attack models .Nowadays, the realization of rerouting anonymous system mainly concentrates to the sender's anonymity, but very little is involved in the receiver's anonymity. Therefore, this thesis has designed an improved rerouting anonymous system model. In order to achieve the goal of concealing the sender, this model has introduced a pseudo- transmission source and the real sender becomes a node of rerouting path, thus realizes the sender's anonymity highly effectively. Simultaneously, it has added a central node to designate the pseudo-transmission source and create the rerouting path for the source node. In fact, the central node does not participate in the transmission of the actual data stream. The data sender cannot be founded even if the central node being monitored. Layer upon layer encryption technology is used to realize the receiver's anonymity. The analysis indicated that the improved model is stable and reliable with good anonymity.