关键词: 主观逻辑, 加权平均, 声誉, 风险

Abstract: P2P system lacks effective mechanism in terms of peers because of its open nature and user anonymity，so its peer trust cannot be evaluated efficiently，and then reliability of the system will be influenced by the possible cheating peers.Aiming at the security problems，a network trust model based on subjective logic theory（created by JΦsang） can be a better solution.The model is to confirm appropriate value of trust degree and the trustiness proportion among the uncertainty by calculating its weighed average and variance.What’s more，risk mechanism is introduced on the basis of the trust model.With the help of all the processes，the trust model can prevent from collaborative cheating and imputation to some degree.According to the simulation analysis，it turns out to be that the trust model is effective to solve the security risk existing in P2P network.

Key words: subjective logic, weighted average, reputation, risk