Abstract State Machines, B and Z

Abstract

Abstract. This paper reports on work in applying ideas from the ABZ world to modern cryptographic protocols. It describes the important differences between this and more "traditional" application areas, and a number of promising approaches in formal methods. DisclaimerThe nature of this paper is such that a bibliography giving decent coverage of the problems raised and attempted solutions from both sides of the fence would take up more than the total space available here -the reader is invited to look elsewhere, e.g. papers and research proposals at [5].

Building a refinement checker for Z

“…The original idea of translating Z into SAL specifications was due to Smith and Wildman [20], however, our implementation has increasingly diverged from the original idea as optimization issues have been tackled. In [9,8] we have described the basics of our implementation, which provides a bespoke parser and generator, written in Java, to translate from the L A T E X encoding of Z into the SAL input language.…”

“…The implementation of this basic strategy is presented in [8], here we recap on its salient points on two examples. Consider the first specification above.…”

“…The built-in types of Z are translated into finite subranges in SAL, according to a scheme described in [8]. For example, N is translated to:…”

“…The guard is followed by a list of assignments, one for each output and primed declaration in the operation schema. This methodology has been implemented in a tool-set, as described in [9,8].…”

A CSP Account of Event-B Refinement

“…Convergent events must not be executed forever, while for anticipated events this condition is deferred to later refinement steps. All of these steps come with precise proof obligations; appropriate tool support helps in discharging these [3,2]. Event-B is essentially a state-based specification technique, and proof obligations therefore reason about predicates on states.…”