Automated Verification of Noninterference Property

摘要

Noninterference is an important information flow model that is widely applied in building secure information systems. Although the noninterference model itself has been thoroughly investigated, verifying the noninterference property in an efficient and automated manner remains an open problem. In this study, we explore the noninterference verification problem from the perspective of the state-equivalence relations between two automata running synchronously. Our results are as follows. (1) To the best of our knowledge, we are the first to propose a recursive form of the necessary and sufficient condition of noninterference. We also for the first time disclose the fact that Rushby's definition of noninterference model can also be formalized as a bi-simulation (over two automata) (2) We present an automated noninterference verification algorithm. The algorithm can finish the verification within O(|S|~2 * |D|), where |D| is the number of security domains and |S| is the number of states. The time-complexity of our algorithm is the best among other existing studies.