Research On Anonymous Communication Mechanism And Control Technology In Distributed Environment

With the development of computer network, security and privacy on Internet are drawing more and more people's attention. In order to resolve the network security and the privacy issues which are concerned by most of the people, key technologies of anonymous communication are gradually gaining in importance as one of the hot domestic and international researches.In this paper, based on the overview of the current research in anonymous communication, we have undertaken a study on the key technologies of anonymous communication and their application problems in large-scale network, focusing on the anonymous communication mechanism, controllability and anonymity measure in distributed environment. The main research work includes:In the typical anonymous communication mechanisms based on key infrastructure, the trusted third party is needed to pre-distribute keys or the key parameters, which can not be applied in complete distributed environment. By using the mechanism of information slicing and the thought of network coding and source routing, a new strategy named ITNC which based on the multi-path network coding is proposed. Then a novel anonymous communication mechanism AC-ITNC without key infrastructure, which uses ITNC to set up the anonymous path, is presented. In the new mechanism, the intermediate nodes involved in coding, the coding coefficients and coded information pieces are delivered separately. It not only improves the security against conspiracy attack but also optimizes the performance of anonymous system. It also provides a new way to achieve anonymous communication in the distributed environment without key infrastructure.Considering the abuse of anonymity, we propose a new revocable anonymous communication model which uses address slicing, signature technology and group management mechanism. It can trace the source IP address of the anonymous abuser while ensuring the anonymity of legitimate users. By introducing group mechanism based on geographic regions, this paper proposes a revocable anonymous communication measure based on location partition, which can improve the anonymity by limiting the nodes within the same geographic region to reduce the number of malicious nodes in the anonymous path. The theoretical analysis and experimental results show that the new measure can effectively improve the anti-collusion attack capability of the system.In this paper some typical anonymity measures are analyzed and limitations of these measures will be highlighted. Then a new anonymity measure based on partial entropy is proposed, in which the anonymity is measured by using the entropy of the probability distribution of some distinct subjects in anonymity set. The new measure can keep the characteristic of entropy measure, and works well on reflecting the degree of difficulty for the attacker to find the targets from the anonymity set. The results of analysis and calculation show that the new measure is preferable for anonymity evaluation.As this paper proposed, the new anonymous communication model, the anonymous abuse control protocol as well as the anonymity measure effectively resolved some of the problems that exist in the practical application of anonymous communication. They also provide the theoretical basis and applied foundation for the application of anonymous communication in distributed environment.