The Research Of Trust Evaluation Algorithm In P2P

In recent years, P2P technology becomes a hot issue which gets more and more people's attention. Based on its distributed feature and the ability to make full use of resources, it has been widely used and rapidly developed. However, the issues of safety and efficiency have gradually appeared, especially lacking guidance and constraint to the behavior of the nodes in the network, which become an important factor in limiting the development of p2p.Therefore, the application of the trust mechanism in P2P network is particularly important in the problems such as the trust value defined and the transfer of trust relation. And the determination of the trust value for each peer becomes the research emphases in trust mechanism. So the research for trust evaluation algorithm provides safeguard for the safety and efficacy of P2P network.P2P network technology is mainly applied in file sharing, collaborative work, equivalence calculation, and search engine. But file sharing is currently one of the most important applications. It allows any end-user namely peer node to complete file exchanging through the network, it is a network system structure that directly exchange resources and services in Shared computers. With the users who use the P2P network sharing files more and more, P2P systems are becoming ever larger. A major challenge of this system is how to confirm a trust relationship between different peers under the condition that without a trusted third party or an authorized center. Meanwhile, the peer must rely on its past behaviors to determine whether it is worthy trusting or not, namely must need to build trust management mechanism.The trust mechanism in P2P network mainly completes the acquisition and analysis of the trust value of nodes in the network to guide decision-making collaboration between nodes, to give the correct trust evaluation in order to prevent all kinds of fraud, to achieve collaboration between nodes, to isolate the untrustworthy nodes. The research of trust mechanism in P2P has focused on proposing a reasonable solution and a algorithm for trust value. Only when the trust value can be calculated as accurately as possible for the node, can it guarantee the security for the interoperability between nodes and ensure the further development of P2P.This thesis summarizes the research results of the existing trust mechanisms. Firstly, analyzes the main factors that influence the trust value and then propose a trust management technology based on the theory of recommended obtaining trust evaluation. Build model based on the theory of fuzzy language variables and fuzzy reasoning. Make trust evaluation for the nodes in P2P network by the direct trust value and recommendation trust value. It divided the network into many groups,according to standard of users'interests.There is a central node to be responsible for the management of the group.This trust mechanism based on the improved trust evaluating algorithms has strengthened the security of P2P system. And by increasing the classification of interest node group and add TTL to control the depth of the search query. Reduce the search scope to improve search efficiency and improve the effectiveness of P2P systems.