Information flow vs. resource access in the asynchronous pi-calculus

Abstract

We propose an extension of the asynchronous π-calculus in which a variety of security properties may be captured using types. These are an extension of the input/output types for the π-calculus in which I/O capabilities are assigned specific security levels. The main innovation is a uniform typing system that, by varying slightly the allowed set of types, captures different notions of security.We first define a typing system that ensures that processes running at security level σ cannot access resources with a security level higher than σ. The notion of access control guaranteed by this system is formalized in terms of a Type Safety Theorem.We then show that, by restricting the allowed types, our system prohibits implicit information flow from high-level to low-level processes. We prove that low-level behavior can not be influenced by changes to high-level behavior. This is formalized as a noninterference theorem with respect to may testing.