Tor Nodes And Links Anonymity Research And Routing Algorithm Improvement

As the most widely used instant anonymous chat software,the Tor network provides related services to more than 2 million users from all over the world every day.However,since the nodes in the Tor network are built by volunteers,they are vulnerable to attacks by malicious users causing the Tor network to fail to provide users with good anonymity;moreover,the current Tor network uses a uniform bandwidth-weighted routing algorithm,which does not eliminate the security risks caused by high bandwidth and meet the different usage demands of users for the Tor network.To address these two problems,this thesis proposes node label-based anonymous evaluation methods LNEAEM and LLHREM for Tor networks,and proposes an improved routing algorithm ABPRA.The main research works are as follows:1)Analyzing Tor network historical node data.The theoreticcal basis of Tor anonymity network and related techniques are described and a large amount of Tor network routing node data provided on the official website of Metrics is collected.By using mathematical statistical analysis,clustering experiments,and Bayesian posterior probability verification,the data are organized and analyzed in detail,and it is found that the attributes of each routing node in the Tor network are unevenly distributed and aggregated among nodes,and the bandwidth attributes of nodes are misleading for node selection.2)Evaluate the anonymity of Tor network.To address the above problems of routing nodes,this thesis proposes the entropybased Tor network anonymity assessment model LNEAEM and the hijacking rate model LLHREM of link attacked by malicious nodes from different labels that nodes have,to assess the anonymity situation of Tor network from the perspective of nodes and links.It is found that the Tor network can provide users with anonymous communication to a certain extent,and the set of nodes under different labels has different entropy performance as well as resistance to compromised node analysis,and the set of nodes with exit labels is more vulnerable.3)Improved routing algorithm.In order to provide users with better anonymity communication services,this thesis proposes an adjustable bandwidth packet routing algorithm ABPRA to improve the shortcomings of the current routing algorithm,and tests the improved Tor source code program by shadow simulation platform.It is found that providing suitable packets for candidate nodes can weaken the negative impact of bandwidth weighting mechanism,and by adjusting the tunable parameters,the routing algorithm can be flexibly adjusted between high anonymity and low latency.The experimental results achieve the expected effect of the algorithm.