Secure Information Flow Analysis Using the PRISM Model Checker

Secure information flow checks whether sensitive information leak to public outputs of a program or not. It has been widely used to analyze the security of various programs and protocols and guarantee their confidentiality and robustness. In this paper, the problem of verifying secure information flow of concurrent probabilistic programs is discussed. Programs are modeled by Markovian processes and secure information flow is specified by observational determinism. Then, two algorithms are proposed to verify observational determinism in the Markovian model. The algorithms employ a trace-based approach to traverse the model and check for satisfiability of observational determinism. The proposed algorithms have been implemented into a tool called PRISM-Leak, which is constructed on the PRISM model checker. An anonymity protocol, the dining cryptographers, is discussed as a case study to show how PRISM-Leak can be used to evaluate the security of programs. The scalability of the tool is demonstrated by comparing it to the state-of-the-art information flow tools.