Abstract: Automated trust negotiation is a way to establish trust for strange peers in the distributed environment.Du-ring negotiation,peers have to not only conceal sensitive information,but also reveal information to strengthen mutual trust,that contradictory situation makes safety and efficiency become the main concern problem for researchers.We proposed a new negotiation model which adds trust file repository and trust evaluation module into the traditional model.Trust file is used to record historical negotiation information of two peers and trust evaluation module is used to eva-luate the trust level of two peers.When negotiation starts,it firstly queries if there is available trust file to be directly used.If it exists,verify it to omit the process of exchanging credentials.Otherwise,it uses the success and fail negotiation times to evaluate their trust level of two peers.Since the trust level of the two negotiators has increased and the sensitivity to the digital credential to each other has decreased,the exchange times of the access control policy and the digital credential will be decreased during the negotiating.Furthermore,it will shorten the time spent and increase the efficiency.By doing experiment in Trustbuilder2,the proposed model is able to increase negotiation efficiency.By analyzing,it is able to protect negotiation form denial of service by using the recorded fail negotiation time.Therefore,the proposed model is safe and efficient.

Key words: Automated trust negotiation,Trust file,Trust evaluation,Negotiation safety,Negotiation efficiency