Grid Environment, Multi-dimensional Trust Model

The concept of Grid originates from Power Grid. Grid links distributed resources of the network together to provide a variety of network services for users. As an important component of Grid technology, Grid security plays a very important role in ensuring the whole Grid system running properly. But, the traditional network security technology has many defects which prompt researchers to try to combine with other technologies to regulate the network order. And, one of the technologies is network trust.Service is the center of Grid, and providing safe and effective service is the main goal of Grid. There are now a lot of researches about trust model deployment strategy and trust evaluation mehod.Based on analysis and research on the existing trust model, a VO (Virtual Organization)-based multi-dimensional trust model is proposed. In this thesis, the VO-based network trust relationships, including direct trust in VO, recommendation trust in VO, direct trust between VOs, recommendation trust between VOs and so on, are analyzed. Among these relationships, the referee in the recommedation trust relationship can be not only an entity, but aslo a trust agent. Then, the evaluation method and computation formula of each trust relationship are presented, and the update strategies of the trust relationship are proposed.Due to the subjectivity and uncertainty of trust, quantitative calculation of trust uncertainty is required for a more accurately reflected change of trust relationships. Because the Dempster-Shafer Evidence Theory has the natural advantages in describing the uncertainty of trust, a Multi-dimensional Trust Model is proposed in this thesis. In the model the conception of Grid trust frame, trust evaluation method and the rules of recommendation trust combination are also presented.The multi-dimensional trust model evaluates the target entity from various subjective perspectives, and gives separately trust evalution to each service provided by the entity. Compared with other trust models, the multi-dimensional trust model can compute every kind of service's trust value more accurately, and meet entity's subjective requirement for diversified services. Thereby, it is possible to locate the service transaction partner more accurately.