A formal framework for confidentiality-preserving refinement

Abstract

Based on a system model consisting of processes describing the machine, the honest users and the adversary, this paper introduces an abstract framework of refinement relations preserving existential confidentiality properties for nondeterministic, probabilistic systems. It allows a refinement step to trade functionality between the machine and its environment, thus shifting the conceptual boundary between machine and environment. A refinement also permits the realization to extend the observational means of an adversary. A confidentiality-preserving refinement relation is defined in terms of another, more basic relation that considers deterministic probabilistic processes. An instantiation with an entropy-based confidentiality property illustrates the use of this framework. The relationship to other concepts of secure refinement, in particular to reactive simulatability, is discussed. © Springer-Verlag Berlin Heidelberg 2006.