Evaluation Of Reputation Under Peer-to-peer Environment

It is necessary to evaluate the peer's reputation efficiently and correctly in order to isolate malicious peers, protect the safety of other peers and improve the service quality and efficiency.A new theory that the beta distribution can be calculated approximately by the normal distribution by the average value area is proofed, a new method which can calculated the reputation vector of peers precisely is proposed based on this theory. To eliminate the calculation error caused by malicious collectives, a reputation evaluation method based on aggregation is proposed. The similarity among peers is calculated according to the reputation their give to the common neighbors and the reputation evaluation value they received from the common neighbors and the reputation they give to each other. Usually all the honest peers can be aggregated to one large group because of their action similarity, while the malicious peers will be aggregated to several small groups because of their different cheating methods. The evaluation result will base on the largest group, by this mean the affection of malicious peers is minimized. To improving the calculation efficiency .All the peers is divided into several groups and calculated respectively, then the reputation is calculated by merge these calculation result. Experiments show that this method can isolate the malicious collectives efficiently.The P2P structure based on traditional de bruijn graph has both less edges and shorter network diameter, while its main shortcoming is that it's too complex to process the insert and leaving of peers, and it also often lead to unevenly distribution of resource among peers. For this reason the routing de bruijn graph and redundant de bruijn routing graph and a new leaving and insert algorithm of peers were proposed. Theoretic analysis and experimental results show that the redundant de bruijn routing graph can simplify the insert and leave operations, and it also can distribute the load among peers evenly.A distributed reputation evaluation method was proposed based on redundant de bruijn routing graph: every peer has redundant routing peers and the peers with higher credit will be selected priorily. The credit of the routing peers is updated by the feedback of the reputation query , so the query accuracy will also improve with the processing of query. Experiments show that the algorithm is suitable for large-scale use of the network environment, and on the base of reliable routing table a robust resouce locating method can be constructed.