Trust model based on dynamic policy similarity for pervasive computing environments

Traditional security mechanisms can not satisfy the pervasive computing environment commendably. A dynamic trust model is proposed, utilizing the Dempster-Shafer (D-S) theory to model the diminution of the hypothesis set on trust evaluation with the accumulation of evidence. The trust expression of relationship between entities, the general formula of direct trust, indirect trust and integrated trust are deduced. With the model presented, anonymous entities can collaborate with trustful parties without central security managers. To avoid or reduce the probability of insecurity brought by inappropriate recommendations, a policy similarity function is adopted in our model to choose proper recommenders. From the simulation results, the mechanism is proved to be advantageous over the other approaches.