A history based semantic aware access control model using logical time

With the advent of semantic technology, access control cannot be done in a safe way unless the access decision takes into account the semantic relationships among the entities in a semantic-aware environment. The SBAC model (semantic based access control model) considers this issue in its decision making process. However, time plays a crucial role in new computing environments, which is not supported in SBAC. In this paper, we propose the temporal semantic based access control (TSBAC) model, as an extension of SBAC, which enhances the specification of user-defined authorization rules by constraining time interval and temporal expression over users' history of accesses. TSBAC uses logical time, rather than to real time, in its authorization rules. A formal semantics for temporal authorizations is provided and conflicting situations (due to the semantic relations of the SBAC model and a sub-interval relation between authorizations) are investigated and resolved in our proposed model. An architecture for the access control system based on TSBAC is presented.