Most model checking techniques for security protocols make a number of simplifying assumptions on the protocol and/or on its execution environment that greatly complicate or even prevent their applicability in some important cases. For instance, most techniques assume that communication between honest principals is controlled by a Dolev-Yao intruder, i.e. a malicious agent capable to overhear, divert, and fake messages. Yet we might be interested in establishing the security of a protocol that relies on a less unsecure channel (e.g. a (...) confidential channel provided by some other protocol sitting lower in the protocol stack). In this paper we propose a general model for security protocols based on the set-rewriting formalism that, coupled with the use of LTL, allows for the specification of assumptions on principals and communication channels as well as of complex security properties that are normally not handled by state-of-the-art security protocol analysers. By using our approach we have been able to formalise all the assumptions required by the ASW protocol for optimistic fair exchange and some of its key security properties. Besides the previously reported attacks on the protocol, we report a new attack on a patched version of the protocol. (shrink)

The article describes the peculiar modality in which design combines predictable and unpredictable elements, and places different disciplinary contributes hosted in this number inside an ordering scheme about possible forms of future’s knowledge.The scheme is built on the intersection of two criteria: the first regards the ways in which the action of invention (expansion of reality) and the action of discovering (expansion of truth) are combined; whilst the second one regards the way in which the unpredictable of the subjects and (...) the predictable of the objects is kept separated (truth explains reality from an external position) or weaved (truth is immanent to reality).Inside this general scheme of combination between predictable and unpredictable, the architectural project has a specific position. The promise of effect that characterizes each architectural project is an action’s strategy that builds programs on predictable elements and produces and exchanges inventions about what is unpredictable. (shrink)

This book constitutes the refereed proceedings of the 4th International Conference on Frontiers of Combining Systems, FroCoS 2002, held in Santa Margherita Ligure, Italy, in April 2002.The 14 revised full papers presented together with 3 invited papers were carefully reviewed and selected from 35 submissions. Among the topics covered are combination of logics, combination of constraint solving techniques, combination of decision procedures, combination problems in verification, modular problems of theorem proving, and the integration of decision procedures and other solving processes (...) into constraint programming and deduction systems. (shrink)