Formal Trust Specification in Service Workflows

The emergence of the Internet has changed the nature of face-to-face towards online interactions. This leads to the concept of virtual interoperation such as Web Services, Grid, and Cloud Computing. Since existing security mechanisms are insufficient to cover the diversity of workflow application domains, trust is considered as an adaptive, high-level abstraction, and platform-independent solution that fits into this context. This paper proposes a formal trust specification which covers a wide range of intuitive trust characteristics such as trust transitivity and mutual relationship. We develop a new trust definition and three modes of trust with algebraic operators to form specification formulas. A method for determining the closeness of a matched trust value on a service using Euclidean Distance is presented and the basic analysis is conducted.