Towards Modal Logic Formalization of Role-Based Access Control with Object Classes

This paper addresses a variation of the role-based access control (RBAC) model with a classification mechanism for objects and a notion of class hierarchies. In the proposed model, the authorization tasks are performed based on the classes instead of the individual objects. This results in more flexibility in terms of security administrative tasks such as downgrading or upgrading individual objects and permission assignments. A formalization for this model is presented using K45 modal logic. The prefixed tableaux method is used to reason about the access control. The required rules for the reasoning process are also presented. The proposed model is applied, via an example to protect the secrecy of the information in a typical organization.