Research On Security Schemes In Complex Peer To Peer Network Systems

In recent years, peer-to-peer network systems have been a wide range ofapplications and development. At the same time, we also see that with theever-expanding network system applications and the ever-progressing networktechnology, an increasing number of peer to peer network systems emerge the trendsuch as a sharp rise in the number of users, the increasing diversity of the networktopology and so on. Peer to peer network systems are becoming more and morecomplex in the direction of development and then emerge complex peer-to-peernetwork systems with the complex characteristics. Faced with this situation, theexisting traditional peer network system of ideas, methods and technology areconfronted with severe challenges and the situation are more obvious in peer-to-peernetwork systems which have characteristics of openness, reciprocity, autonomy andarbitrariness, etc. All of these causes make security issues in a complex peer-to-peernetwork system increasingly prominent. Therefore, how to design and researchsecurity mechanisms in complex peer to peer network systems, is a difficult focus inthe complex peer-to-peer network systems and is also a hot issue which needs to solvein the complex peer to peer network systems. Based on the former research, we read alarge number of existing related references of the theory of peer to peer network andthe theory of security mechanism then we do some in-depth analysis and study of thesecurity problems in the complex peer to peer network systems. According to ourresearch, we proposed effective solutions to these security problems and also havemade certain scientific research achievements.The main contents of this thesis contain the following three aspects:1．We do research on how to create a trust relationship among peers in thecomplex peer to peer network systems, mainly focus on how to use the value of apeer's reputation to conduct a comprehensive assessment of the credibility.Specifically, we analyzed the shortcomings and deficiencies of the trust mechanism in the existing peer to peer network systems and then we given some possiblebreakthroughs and solutions to these problem. At the same time, we analyzedassessment factors of a peer's reputation value based on subjective logic model andrelated theoretical knowledge including the fact that space and conceptual space. Thenwe can obtain the calculation method of peers' the direct reputation value and indirectreputation value from two aspects of the direct trust evaluation of the indirect trustevaluation. In this way, we proposed a trust mechanism based on the assessment ofthe global reputation value.2．We do research on how to achieve anonymous communication processbetween the peers in the complex peer to peer network systems. In order to theanonymous, efficient and secure communication relations among peers in the networksystem of in the complex peer to peer network systems, we proposed two anonymousmechanisms. The first mechanism is mainly based on pseudonyms transform meansand then achieves anonymous communication between peers. At the same time, wegiven the performance analysis compared to the exiting anonymous mechanism. Thesecond mechanism is mainly based on blind signature way and then we design anoptimized anonymous algorithm. Also we gave the performance analysis of thisanonymous mechanism.3．We do research on how to do the performance recovery against an attackedand destroyed complex peer to peer network system based on complex network theoryand then give some corresponding security mechanisms. Specifically, we firstly dothe analysis and research on the characteristic parameters in complex peer to peernetwork systems based on complex network theory. Secondly, we do some researchfrom these three aspects of how to restore the power-law characteristics in thecomplex peer to peer network systems, how to restore the value of high degree peersin the complex peer to peer network systems and how to restore the networkconnectivity in the complex peer to peer network systems. On this basis, we proposedan anti-attack model based on complex network theory.The innovation works in this thesis mainly have:1．To establish a trust relationship between peers in complex peer to peernetwork systems, we proposed a new trust mechanism based on the assessment of theglobal reputation value. In this mechanism, we have made a comprehensive andintegrated assessment of the reputation value of peers from two aspects of the directtrust evaluation of the indirect trust evaluation based on based on the transference ofreputation value between peers, the patriarch judgments of the reputation value. Simulation results show that, compared with the normalized assessment mechanismand non-normalized evaluation mechanism, the proposed mechanism based on theassessment of the global reputation of trust mechanism is significantly better than thetwo existing evaluation mechanism from the two prospective of the evaluate successrate and the number of the evaluation success peers. Therefore, the proposed trustmechanism has a certain degree of rationality.2．To establish an anonymous communication relation between peers in complexpeer to peer network systems, we proposed two anonymous mechanisms in this thesis.In the first mechanism, we related a peer's dynamic pseudonyms to its onlycorresponding macro value based on the pseudonyms' transform. In this way, weensured the communication identifiable information's hidden between peers and thenwe achieved anonymous communication between peers. In the second mechanism, wedesign a anonymous mechanism using the theory based on blind signature algorithmfrom anonymity and computing costs. At the same time, using the blind signatureprocess of a trusted third party, we ensured the communication identifiableinformation's hidden between peers and then we achieved anonymous communicationbetween peers.3．To analyze the network characteristics of complex peer to peer networksystems, based on complex network theory, we made some analysis from two anglesof the peer's degree distribution and shortest path between peers. The simulationresults show that the calculation method of peer degree distribution, based on themodel of the scale-free network, can accurately describe the characteristics of peerdegree distribution in complex peer to peer network systems. At the same time, thetheoretical result of the shortest path between peers using our proposed calculationmethod in complex peer to peer network systems is basically the same to the actualsimulation result.4．To restore a destroyed complex peer to peer network system under attack,based on complex network theory, we proposed an anti-attack model. As we know,for a complex peer to peer network system with complex nature, the network'spower-law characteristic, the peers of high degree values and the networkconnectivity between peers are the three aspects to maintain the normalcommunication function and transfer function. Therefore, we designed correspondingrecovery mechanisms and algorithms to the possible destruction above. In this wayour complex peer to peer network system can obtain an anti-attack of malicious peers.The simulation results show that, our proposed anti-attack model can make a destroyed peer to peer network system after being attacked by some malicious peersbeing done corresponding recovery and compensation and then the peer to peernetwork systems using an anti-attack model can have certain anti-attack ability andanti-damage ability.