Research Of Hybrid Trust Models In P2P Systems

A P2P trust model is one of the effective approaches to solve the security problems of P2P networks. However, there are many weaknesses in existing trust models, such as the heavy network overload due to the complexity of trust value calculation, the ineffective prohibition of "free-riding" issue. Therefore, how to optimize the process of trust value calculation, reduce network load and encourage peers to share their resources, have become the key points of this research.According to the analysis of existing trust models in China and abroad, a hybrid trust model in P2P systems was proposed, which was set up by reference to process of trust establishment in real society and management of firms and cooperations between firms. In the model, in order to solve the problem of network overload caused by adopting real-time method of calculating trust value in existing trust models, a calculation method of trust value based on feedback of transactions between peers was proposed. At the same time, for the sake of the alleviating "free-riding" issue in P2P network, an incentive mechanism based on the way resource distribution was also proposed.In calculation method of trust value based on evaluating feedback of transaction between peers, the calculation of trust value was finished by the use of the value of peer's feedback. The trust value depends on the value of peer's feedback, and reflects the peer's credible degree in P2P systems.The incentive mechanism based on resource distribution way, that peers take advantage of the key factor which they can get reliable resource, and by referring to requester's trust value, distribute corresponding trust value of the service resources, to limit the capability of the peer access to resource. In this mechanism, peer increases the power of sharing resources, and enhances the utilization rate of P2P systems.Through comparison between the HTM model and other hybrid trust models, the simulation results proved that the HTM model has better performance in security, protecting against the malicious peers and the prohibition of "free-riding" issue than other hybrid trust models.