Semantic properties of μ-charts

μ-Charts are a Statechart-like language which is designed for specifying reactive systems. This paper extends the language of μ-charts with a new parallel operator; it defines a formal semantics for the language, and then it explores the semantic properties of the extended language. The paper concludes with a simple case study to illustrate how the language may be used to specify and reason about reactive systems.

Extending the theory of Owicki and Gries with asynchronous message passing

We describe an extension of the theory of Owicki and Gries (1976) to a programming language that supports asynchronous message passing based on unconditional send actions and conditional receive actions. The focus is on exploring the fitness of the extension for distributed program derivation. A number of experiments are reported, based on a running example problem, and with the aim of exploring design heuristics and of streamlining derivations and progress arguments.

A Z based approach to verifying security protocols

Security protocols preserve essential properties, such as confidentiality and authentication, of electronically transmitted data. However, such properties cannot be directly expressed or verified in contemporary formal methods. Via a detailed example, we describe the phases needed to formalise and verify the correctness of a security protocol in the state-oriented Z formalism.

Formal verification of type flaw attacks in security protocols

Security protocols are often modelled at a high level of abstraction, potentially overlooking implementation-dependent vulnerabilities. Here we use the Z specification language's rich set of data structures to formally model potentially ambiguous messages that may be exploited in a 'type flaw' attack. We then show how to formally verify whether or not such an attack is actually possible in a particular protocol using Z's schema calculus.