Modeling and verifying TESAC using CSP

Cloud computing is an emerging computing paradigm in IT industries. The wide adoption of cloud computing is raising concerns about management of data in the cloud. Access control and security are two critical issues of cloud computing. Time efficient secure access control (TESAC) model is a new data access control scheme which can minimise many significant problems. This scheme has better performance than other existing models in a cloud computing environment. TESAC is attracting more and more attentions from industries. Hence, the reliability of TESAC becomes extremely important. In this paper, we apply Communication Sequential Processes (CSP) to model TESAC, as well as their security properties. We mainly focus on its data access mechanism part and formalize it in detail. Moreover, using the model checker Process Analysis Toolkit (PAT), we have verified that the TESAC model cannot assure the security of data with malicious users. For the purpose of solving this problem we introduce a new method similar to digital signature. Our study can improve the security and robustness of the TESAC model.