The Study Of Network Anonymity Based On Crowds

The rapid development of the Internet makes people to pay more attention to their privacy and security issues in the network.As a privacy protection technology,anonymity communication is paid more and more attention by researchers.Crowds is one kind of P2P anonymity communication system for anonymous Web browsing.It provides anonymious services by building rerouting path based on a fixed forwarding probability.Crowds anonymity communication system spends less and has a good scalablity.With the development of P2P technology,research about Crowds anonymity communication system has become a hot topic in the field of anonymity communication.Firstly,this paper reviews the related anonymity communication technologies,and highlights the principle and research situation of Crowds.Then this paper analyzes the safety,performance,quantitative degree of anonymity and improvement methods of Crowds.Secondly,F-Crowds is proposed in this paper based on the principle of Crowds,which can provide an anonymous file sharing scheme for BitTorrent.A kind of node named F-Node is introduced in F-Crowds to provide an anonymous layer for BitTorrent,so it can has a certain degree of anonymity.F-Crowds adopts the probability forwarding strategy of Crowds,which can provide users with an adjustable degree of anonymity in order to meet the different needs of different users for performance and anonymity.In addition,this paper also presents a node selection policy based on the level of degree of anonymity and location,which can ensure not only efficiency and anonymity but also can assure that the users who enjoy greater anonymity will provide more anonymity protection for other users at the same time.Finally,the analyses of F-Crowds are carried out.Firstly,this paper analyzes the ability of F-Crowds to resist N-1 Attack,Message Coding Attack,Time Attack and Message Volume Attack,and computes the successful probability of resisting the Predecessor Attack of F-crowds,and also compares that with Crowds system.Secondly,this paper calculates the average path length of F-Crowds,and analyzes the degree of anonymity of F-Crowds quantitatively by using the information entropy theory.At last,this paper simulates the F-Crowds by using the PeerSim simulation tool,which shows the influence of forwarding probability on the download time.