This paper proposes rewriting logic as an executable specification formalism for security protocols that offers some novel advantages. A messagepassing object-oriented approach seems particularly natural for communication protocols and can be naturally formalized in rewriting logic. This is illustrated by using the Needham-Schroeder Public-Key protocol as a running example. The rewriting logic-based Maude interpreter [CELM96] offers also some useful advantages. Efficient executability allows prototyping and debugging of protocol specifications. But since a concurrent system can have many different behaviors, to properly analyze the system it becomes important to explore not just the single execution provided by some default strategy, but many other executions. Maude supports user-defined execution strategies, including strategies such as breadth-first-search that can exhaustively explore all the executions of a system. This is very helpful in uncovering security flaws under unforeseen ...

Rewriting logic expresses an essential equivalence between logic and computation. System states are in bijective correspondence with formulas, and concurrent computations are in bijective correspondence with proofs. Given this equivalence between computation and logic, a rewriting logic axiom of the form t \Gamma! t 0 has two readings. Computationally, it means that a fragment of a system 's state that is an instance of the pattern t can change to the corresponding instance of t 0 concurrently with any other state changes; logically, it just means that we can derive the formula t 0 from the formula t. Rewriting logic is entirely neutral about the structure and properties of the formulas/states t. They are entirely user-definable as an algebraic data type satisfying certain equational axioms. Because of this ecumenical neutrality, rewriting logic has, from a logical viewpoint, good properties as a logical framework, in which many other logics can be naturally represented. And, computationally, it has also good properties as a semantic framework, in which many different system styles and models of concurrent computation and many different languages can be naturally expressed without any distorting encodings. The goal of this paper is to provide a relatively gentle introduction to rewriting logic, and to paint in broad strokes the main research directions that, since its introduction in 1990, have been pursued by a growing number of researchers in Europe, the US, and Japan. Key theoretical developments, as well as the main current applications of rewriting logic as a logical and semantic framework, and the work on formal reasoning to prove properties of specifications are surveyed.

Abstract not found

In this paper we give an empirical evaluation of an object-oriented method which we applied to the modelling of a complex industrial information system. We describe our methodology consisting of different notations and guidelines. We also briefly show a CASE environment that we are developing for supporting our methodology. At last, we report our experiences gained during the modelling process.

Data Type Specification, in combination with modal logics for formalizing the process of building systems from interconnected components. This combination of logical and categorical techniques has also been applied to parallel program design languages in the style of UNITY [14] and IP [41], providing semantics for modularization techniques based on the notion of superposition. This has resulted in the development of a programming design language called Community [33]. Two formalisms that provide explicit support for object systems and can reason about their rewriting logic specifications have been recently developed. One is a version of the modal -calculus proposed by Lechner [48, 49] for reasoning about object-oriented Maude specifications. Another is Denker's objectoriented distributed temporal logic DTL + [24, 22], that extends the DTL and D 1 distributed object temporal logics of Ehrich and Denker [30, 23, 29]. Lechner [48, 49] uses her version of the modal -calculus to identif...

Tool support helps developers of information systems to considerably increase the accuracy and quality of its models. The use of formal languages in the conceptual modelling process allows the construction of powerful validation tools by executing the model. Executing a model is a very difficult task, when not impossible, due to the high level of abstraction in which it is described. In this paper we analyse some aspects to be taken into account when executing models specified with the formal object-oriented language Troll.