In my Wish List, an Automated Tool for Fail-Secure Design Analysis: an Alloy-Based Feasibility Draft

A system is said to be fail-secure, sometimes confused with fail-safe, if it maintains its security requirements even in the event of some faults. Fail-secure analyses are required by some validation schemes, such as some Common Criteria or NATO certifications. However, it is an aspect of security which as been overlooked by the community. This paper attempts to shed some light on the fail-secure field of study by: giving a definition of fail-secure as used in those certification schemes, and emphasizing the differences with fail-safe; and exhibiting a first feasibility draft of a fail-secure design analysis tool based on the Alloy model checker.Comment: In Proceedings ESSS 2014, arXiv:1405.055

Distributed Implementation of SIGNAL: Scheduling & Graph Clustering

International audienceThis paper introduces the scheduling strategy and some key tools which have been designed for the distributed implementation of Signal, a real-time synchronous dataflow language. First, we motivate a scheduling strategy with respect to the reactivity and time-predictability requirements bound to real-time computing. Then, several key tools to implement this scheduling strategy are described. These tools are acting on the concept of Synchronous-Flow Dependence Graph (SFD Graph) which defines a generalization of Directed Acyclic Graph and constitutes the abstract representation of Signal programs. The tools presented in this paper are: (a) the abstraction of SFD graphs which enables grain-size tuning according to the target architecture, (b) the notion of scheduling over SFD graphs and (c) qualitative clustering tools based on the notion of Compositional Deadlock Consistency

An algebraic theory for behavioral modeling and protocol synthesis in system design

International audienceThe design productivity gap has been recognized by the semiconductor industry as one of the major threats to the continued growth of system-on-chips and embedded systems. Ad-hoc system-level design methodologies, that lifts modeling to higher levels of abstraction, and the concept of intellectual property (IP), that promotes reuse of existing components, are essential steps to manage design complexity. However, the issue of compositional correctness arises with these steps. Given components from different manufacturers, designed with heterogeneous models, at different levels of abstraction, assembling them in a correct-by-construction manner is a difficult challenge. We address this challenge by proposing a process algebraic model to support system design with a formal model of computation and serve as a type system to capture the behavior of system components at the interface level. The proposed algebra is conceptually minimal, equipped with a formal semantics defined in a synchronous model of computation. It supports a scalable notion and a flexible degree of abstraction. We demonstrate its benefits by considering the type-based synthesis of latency-insensitive protocols, showing that the synthesis of component wrappers can be optimized by behavioral information carried by interface type descriptions and yield minimized stalls and maximized throughput

Toward Static Analysis of SIGNAL Programs using Interval Techniques

International audienceThis paper presents a work-in-progress aiming at improving the functional analysis of Signal programs. The usual adopted technique relies on abstractions. Typically, in order to check the presence or absence of variables in a program at some logical instants, the program is transformed into another program that reflects its clock information so that the presence or absence of each variable can be straightforwardly checked. Signal adopts a boolean abstraction for the static functional analysis of programs. This abstraction does not enable to fully reason on the values of non logical variables. Here, we propose a solution based on interval techniques in order to be able to deal with both logical and numerical parts of programs

Synchronous programming with events and relations: the SIGNAL language and its semantics

AbstractIn this paper, systems which interact permanently with their environment are considered. Such systems are encountered, for instance, in real-time control or signal processing systems, C3-systems, man-machine interfaces, to mention just a few. The design and implementation of such systems require a concurrent programming language which can be used to verify and synthesize the synchronization mechanisms, and to perform transformations of the concurrent source code to match a particular target architecture. Synchronous languages are convenient tools for such a purpose: they rely on the assumption that: (1) internal actions of synchronous systems are instantaneous, and (2) communication with the environment is performed via instantaneous flashes involving some external stimuli. In this paper, we present a synchronous programming language: SIGNAL. A SIGNAL program specifies dynamical relations between (internal and external) signal flows. The SIGNAL compiler checks deadlock and determinism of the program, and produces an intermediate level code equivalent to a nested family of concurrent automata. The compilation algorithm is supported by: (1) a behavioural semantics of SIGNAL programs in terms of conditional rewriting rules, (2) the coding of this semantics into the skew product of a dynamical system over the field of integers modulo 3 and directed graphs, (3) an algebraic algorithm to transform the above coding into an equivalent executable one, which provides by the way an execution semantics of the language. We briefly discuss the implementation aspects, and explain the capabilities and limitations of the current version of the SIGNAL compiler

Industrial Experience Report on the Formal Specification of a Packet Filtering Language Using the K Framework

Many project-specific languages, including in particular filtering languages, are defined using nonformal specifications written in natural languages. This leads to ambiguities and errors in the specification of those languages. This paper reports on an industrial experiment on using a tool-supported language specification framework (K) for the formal specification of the syntax and semantics of a filtering language having a complexity similar to those of real-life projects. This experimentation aims at estimating, in a specific industrial setting, the difficulty and benefits of formally specifying a packet filtering language using a tool-supported formal approach

Système de recherche de méthodes Java basé sur leur signature

L'objectif de cet article est de proposer une démarche permettant de mettre en place un moteur de recherche de méthodes au sein d'un langage de programmation. Un tel outil s'avère particulièrement utile aux développeurs. Des solutions ont déjà été proposées mais elles sont pour la plupart basées sur une recherche textuelle, c'est-à-dire uniquement basées sur le contenu textuel de la description des différentes méthodes. Nous proposons dans cet article une nouvelle approche basée sur la signature des méthodes. Le langage utilisé tout au long de cet article est le langage Java

Real-time,synchronous,data-flow programming: the language "SIGNAL" and its mathematical semantics

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Hybrid dynamical systems theory and the language "SIGNAL"

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