Abstract: In order to decrease the risk of exchange,increase the rate of successful exchange,and make the P2P file sharing system to develop continually, a reputation model based on interest group was proposed, and relevant peer reputation calculating method, file exchanging process, access controlling strategy were designed. The reputation model is derived from the thought of human community, and keeps away from the shortage of the whole trust model and the partial trust model. All peers arc grouped by the type of their resources, thus the efficiency of file exchange is higher, and the security of the network is stronger. Our simulation experiments and theoretical analysis of the reputation model prove that our model has the characteristics of correctness and feasibility. Compared with the former trust models, the model has higher maturity and security.

Key words: P2P network,File sharing system,Reputation model,Interest group