Using Graph Theory to Represent a Spatio-Temporal Role-Based Access Control Model

Pervasive computing applications have unique characteristics that preclude the use of traditional access control models, such as Role-Based Access Control (RBAC), for their protection. Such models do not take into account contextual information before making access decisions and cannot handle the dynamism inherent in pervasive computing applications. Towards this end, we propose new spatio-temporal access control models for use in such applications and formally define their semantics using graph-theoretic notation. The dynamism inherent in pervasive computing applications may cause the access control configuration to change while the policies are deployed. Towards this end, we show how to perform incremental analysis to give assurance that security breaches do not occur as a result of changing the access control configuration. Our analysis makes clever use of data structures and achieves good time complexity results.