A unified taxonomy framework of trust
In this chapter, we provide a formal definition of trust relationship with a strict mathematical structure that can reflect many of the commonly used notions of trust. Based on this formal definition, we propose a unified taxonomy framework of trust. Under the taxonomy framework, we discuss classification of trust. In particular, we address the base level authentication trust at the lower layer and a hierarchy of trust relationships at a higher level. We provide a set of definitions, propositions, and operations based on the relations of trust relationships. Then we define and discuss properties of trust direction and trust symmetry. We define the trust scope label in order to describe the scope and diversity of trust relationship. All the definitions about the properties of trust become elements of the unified taxonomy framework of trust. Some example scenarios are provided to illustrate the concepts in the taxonomy framework. The taxonomy framework of trust will provide accurate terms and useful tools for enabling the analysis, design, and implementation of trust. The taxonomy framework of trust is first part of research for the overall methodology of trust relationships and trust management in distributed systems.