Modelling and Verification of Dynamic Role-Based Access Control

Controlling access to resources is essential for ensuring correctness of system functioning. Role-Based Access Control (RBAC) is a popular authorisation model that regulates the user's rights to manage system resources based on the user's role. In this paper, we extend the traditional static approach to defining RBAC and propose as well as formalise a dynamic RBAC model. It allows a designer to explicitly define the dependencies between the system states and permissions to access and modify system resources. To facilitate a systematic description and verification of the dynamic access rights, we propose a contract-based approach and then we demonstrate how to model and verify dynamic RBAC in Event-B. The approach is illustrated by a case study - a reporting management system.