Research And Implementation Of P2P File-sharing System Based On Trust

It is reported by ipoque, an Internet research institute, that P2P technology has dominated Internet and 50-90% of the total flow is from P2P systems. Because of the natures of P2P, such as distribution, autonomy, fault-tolerance, and expandability, P2P technology has been used widely in file sharing systems. P2P systems have become effectual resource-sharing models in the Internet. Compared with conventional C/S systems, P2P file sharing systems settle the problems such as slow respondence and overweight load.Although the applications of P2P develop extensively, P2P file sharing systems bring potential security hazards, and lack available mechanisms to improve the usability of systems. Users needn't take responsibility for themselves, so fraud actions and irresponsible services exist in the applications. It is difficult to ensure the service quality. Trust relationship is built by reliable third party in traditional centralized trust mechanisms, but it is infeasible in P2P network. In this paper, a P2P file sharing system based on trust is designed and implemented. The system is based on JXTA platform, and adopts a P2P trust mechanism, which is composed of the dynamic trust model and the trust mechanism based on group.Trust model is the most important component in P2P trust mechanism. On the basis of literatures review, advantages and disadvantages of existing trust models are analyzed in this paper, and a novel trust model based on reputation and risk is proposed. The trust model based on reputation could recognize malicious peers effectively to avoid malicious activities. The innovation is analyzing the natures of P2P, appending risk with trust model based on reputation, and considering the reputation of providers. RR-Trust model, obtains a value via fuzzy evaluation, integrates local reputation with global reputation, and finally provides a selection scheme. According to practical application, JXTA protocols are studied and trust mechanism is proposed based on group. Most of peers have same tasks and interests, so it is necessary to build the trust measure combining authentication with encouragement.The trust model and trust mechanism based on group are applied to P2P file sharing system, and through the searching and quantization the historical activities, the model could recognize action, and finally makes decision depending on peer trust. The reliability of the system is ensured to a certain extent. Malicious peers are restrained and good peers are encouraged. So the activities are standardized, and successful transaction rate is raised.