Abstract: The characteristics of P2P networks are open， anonymous， and loosely coupled internode， which lead to false resources， malicious evaluation， and syndicates， etc. To solve this problem， a related cluster based trust model for P2P networks named RCTrust was presented. Nodes were gathered in clusters according to their interest similarity and communication history. Trust relation was categorized into two kinds according to the cluster which communication target was belonging to and subsequently each solution for these kinds was also put forward. In RCTrust， measure of node communication success rate， communications history similarity， honesty and timeliness of evaluation were used as reference parameters to evaluate the credit of peers. Simulation results showed that robustness against malicious attacks was obtained and a high rate of successful communication was provided by the proposed model.

Key words: P2P trust model, related cluster, communication history similarity, malicious node, P2P security