Anonymity Measure And Protocol Research In P2P Anonymous Communication System

With the extensive application of computer networks, Internet security and privacy draws people's attention increasingly. Anonymous communication technology, because of its ability which can well hide communication relationship, becomes the interesting research area for network security researchers. Recently, with the proliferation and great success of P2P technology, P2P provides a new technical means which can solve anonymous communication problems. More and more researchers pay their attention on the design of P2P anonymous communication protocol. Meanwhile, the objective of various anonymous technologies is obtaining the anonymity. The research of anonymity measure has an important guiding significance to the improvement of anonymous system. Aimed at strong anonymity and high efficiency in P2P anonymous communication system, this thesis mainly discusses the method of anonymous measure and P2P anonymous communication protocol. Firstly, this thesis explicates the correlative concept of anonymouscommunication technology and P2P technology, and introduces the main realization mechanism of anonymous communication. It analyzes the trait of various anonymous systems and points out the current situation, develop trend and existent problem. The representative P2P anonymous communication systems are also discussed, and a summarization to common attacks is given.Secondly, anonymity measure status of P2P anonymous system is only quantitatively analyzing sender anonymity. In this thesis, the measure method of receiver anonymity is studied. Based on information entropy, in allusion to collusion attack, the computational methods of receiver anonymity measure for several kinds of typical P2P anonymous systems are given. And mathematic analysis is provided for the relationship among receiver anonymity, the size of system, the proportion of malicious node, the length of rerouting path and forwarding probability.Finally, because trade off anonymity and efficiency is a very difficult problem in P2P anonymous communication systems, intention to acquiring strong anonymity, reducing the price and improving efficiency, this thesis proposes LCPACP, a new Length Controllable Protocol for P2P anonymous communication. LCPACP uses nested encryption to guarantee strong anonymity and adopts forwarding probability decreasing strategy to control path length to obtain high efficiency. The theory analysis and calculation results show that this protocol can not only shorten path and ensure well transmission performance, but also can provide good anonymous protection.