Adaptive Policy Evaluation Framework for Flexible Service Provision

In the past decade, the framework of service polices has been established to ensure the transparency and accountability of operations of ICT services. This is generally called a "trust framework." The framework provides trust to its participants, in which economical operations are enabled. A modern framework of services are enpowered by IoT, where the environments often change in time. Here, we have to re-evaluate the policies when we observe changes in the environments. In this paper, we propose a formal model of adaptive policy evaluation framework that reflects the trust for the evaluation policy and the collection of environmental data by IoT devices. PDP runs under a given trust circle, receives assertions including policies of peers, and make a decision. Furthermore, we formalize the adaptive evalua- tion scheme of policies that reflects the dynamics of a trust circle which is affected by the environment of PDP. Monitor plays an essential role in controlling the trust circle by sensing the dynamic change of environments, which gives growth or shrink of a trust circle.