Research Of Negotiation Mechanisms Of ATN In Open Environments

An automated trust negotiation (ATN) achieves the trust establishment between twostrangers in open environments by means of negotiating mechanism. The core contents ofnegotiating mechanisms include access control policies and negotiation strategies, which havesome main problems nowadays, including: excessively complex rules of access controlpolicies maybe can lead to policy conflicts, negotiating strategies lack security and thenegotiating efficiency is low. Therefore, design of methods which can test whether policieshave conflicts, and implement of a safe and high efficient negotiating strategy based onexistent strategies are the primary focus of this research.An extended policy structure based on the structure of the traditional access controlpolicy was designed, it was used to reduce the number of the disclosure policies during thealternately process and make the negotiating’s speed become faster. Through summarizing thereasons causing the conflict within policies, in order to determine if the policies had conflicts,the exhaust-testing algorithm and simplified-partition algorithm called policy validity testingmethods were brought forward, and some plans used to solve the conflict were supplied so asto prevent the unnecessary negotiating failure from being occurred and enhance thenegotiating success rate.A finite automaton based strategy was proposed, which was improved on the basis ofprudent strategy, compared with eager strategy, it was provided with security. The strategyusing finite automaton acted as the graph theory tool to analyze the process of ATN and therules of access control policies, and a memory chain structure that was used to reduce thenumber of negotiating interaction was devised, compared with prudent strategy, the strategyhad higher negotiating efficiency.A Trust-History based ATN (THATN) model was designed, in which the trust historymodel, policy validity testing model and the finite automaton based strategy were added to thetraditional model. The fast negotiating that could enhance the negotiating efficiency in somecondition was implemented by the trust history model in THATN. The policy validity testingmodel could prevent the unnecessary negotiating failure from being occurred and enhance thenegotiating success rate.The simulation experiment results when the finite automaton based strategy comparedwith other negotiating strategies in the aspect of negotiating efficiency showed that as theproportion of the repeat credentials in access control policies increased, the negotiatingefficiency of the finite automaton based strategy was higher. The simulation experiment results about policy validity testing model and trust history model showed that the policyvalidity testing model could improve the negotiating success rate and the trust history modelcould enhance negotiating efficiency. The simulation experiment results when the THATNcompared with the traditional negotiating model in the aspects of negotiating efficiency andnegotiating success rate showed that the success rate and the negotiating efficiency were bothimproved in THATN.