What Semantic Equivalences Are Suitable for Non-interference Properties in Computer Security

Abstract

Non-interference properties are an important class of security properties. Many different non-interference properties have been presented based on different underlying models including the process algebraic languages. Usually, in specifying the non-interference properties using process algebraic languages, a specific semantic equivalence is introduced. Though weak bisimulation based non-interference properties have been studied extensively, it is not always satisfactory. This paper considers the topic on pursuing a probably more suitable semantic equivalence for specifying the non-interference properties. We find several alternatives, e.g., should testing equivalence, impossible future equivalence and possible future equivalence, etc. As another topic in the paper, based on the structural operational semantics, we suggest a compositional rule format, the SISNNI format, for an impossible future equivalence based non-interference property, i.e., the SISNNI property. We show that the SISNNI property is compositional in any SISNNI languages, i.e., languages in the SISNNI format.