Measurement And Improvement Of Tor Anonymous System

With the fast development of Internet, users can communicate and share information rapidly. User's security and privacy has gained more and more attention.The conventional encryption technology can only ensure the secrecy of the correspondence content itself., however the attacker can obtain the IP addresses of the sender and receiver, thus deduce the identities of the correspondent. Anonymity means not revealing who is communicating with whom, and how often, which has been the basis requirement of many network application, such as anonymous electronic voting, offence report, E-commence, E-money and so on.Firstly, this paper gives a survey of anonymity systems, then focuses on the most popular anonymous communication system(Tor). we gave an active measurement on real deployed Tor system, and obtained circuit latency, circuit throughput and the attributes of Tor routers, which include scale, state, survival time, geopolitical distribution and bandwidth. With these parameters, we analyzed the effect of these characteristics on anonymity and usability of Tor, then gave advices on improving Tor setting and design.Through measurement and study of Tor, we obtain the bottlenecks the Tor . Aiming at one of the most important bottlenecks, we propose latency-prior router selection algorithm. Every Tor router measures latency to other Tor routers. Though these latency information, Tor client selects Tor router in order to reduce latency. Compare to original Tor router algorithm, this algorithm improve latency and usability of Tor.Meanwhile in order to measure and study Tor, we implement Tor client. Then we describe the major module of Tor client in detail.