Jean-François Couchot
University of Franche-Comté
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Publication
Featured researches published by Jean-François Couchot.
Journal of the Brazilian Computer Society | 2003
Jean-François Couchot; David Déharbe; Alain Giorgetti; Silvio Ranise
We present a technique to prove invariants of model-based specifications in a fragment of set theory. Proof obligations containing set theory constructs are translated to first-order logic with equality augmented with (an extension of) the theory of arrays with extensionality. The idea underlying the translation is that sets are represented by their characteristic function which, in turn, is encoded by an array of Booleans indexed on the elements of the set. A theorem proving procedure automating the verification of the proof obligations obtained by the translation is described. Furthermore, we discuss how a sub-formula can be extracted from a failed proof attempt and used by a model finder to build a counter-example. To be concrete, we use a B specification of a simple process scheduler on which we illustrate our technique.
The Computer Journal | 2012
Jacques M. Bahi; Jean-François Couchot; Christophe Guyeux
This research work presents a new class of non-blind information hiding algorithms that are stego-secure and robust. They are based on some finite domains iterations having the Devaney’s topological chaos property. Thanks to a complete formalization of the approach we prove security against watermark-only attacks of a large class of steganographic algorithms. Finally a complete study of robustness is given in frequency DWT and DCT domains.
fundamentals of computation theory | 2011
Jacques M. Bahi; Jean-François Couchot; Christophe Guyeux; Adrien Richard
Chaotic functions are characterized by sensitivity to initial conditions, transitivity, and regularity. Providing new functions with such properties is a real challenge. This work shows that one can associate with any Boolean network a continuous function, whose discrete-time iterations are chaotic if and only if the iteration graph of the Boolean network is strongly connected. Then, sufficient conditions for this strong connectivity are expressed on the interaction graph of this network, leading to a constructive method of chaotic function computation. The whole approach is evaluated in the chaos-based pseudo-random number generation context.
International Journal of Bioscience, Biochemistry and Bioinformatics | 2014
Bassam AlKindy; Jean-François Couchot; Christophe Guyeux; Arnaud Mouly; Michel Salomon; Jacques M. Bahi
Due to the recent evolution of sequencing techniques, the number of available genomes is rising steadily, leading to the possibility to make large scale genomic comparison between sets of close species. An interesting question to answer is: what is the common functionality genes of a collection of species, or conversely, to determine what is specific to a given species when compared to other ones belonging in the same genus, family, etc. Investigating such problem means to find both core and pan genomes of a collection of species, \textit{i.e.}, genes in common to all the species vs. the set of all genes in all species under consideration. However, obtaining trustworthy core and pan genomes is not an easy task, leading to a large amount of computation, and requiring a rigorous methodology. Surprisingly, as far as we know, this methodology in finding core and pan genomes has not really been deeply investigated. This research work tries to fill this gap by focusing only on chloroplastic genomes, whose reasonable sizes allow a deep study. To achieve this goal, a collection of 99 chloroplasts are considered in this article. Two methodologies have been investigated, respectively based on sequence similarities and genes names taken from annotation tools. The obtained results will finally be evaluated in terms of biological relevance.
intelligent information hiding and multimedia signal processing | 2011
Jacques M. Bahi; Jean-François Couchot; Christophe Guyeux
Chaos-based approaches are frequently proposed in information hiding, but without obvious justification. Indeed, the reason why chaos is useful to tackle with discretion, robustness, or security, is rarely elucidated. This research work presents a new class of non-blind information hiding algorithms based on some finite domains iterations that are Devaneys topologically chaotic. The approach is entirely formalized and reasons to take place into the mathematical theory of chaos are explained. Finally, stego-security and chaos security are consequently proven for a large class of algorithms.
Lecture Notes in Computer Science | 2007
Fabrice Bouquet; Jean-François Couchot; Frédéric Dadeau; Alain Giorgetti
Model-based testing is bound, by essence, to use the enumerated data structures of the system under test (SUT). On the other hand, formal modeling often involves the use of parameterized data structures in order to be more general (such a model should be sufficient to test many implementation variants) and to abstract irrelevant details. Consequently, the validation engineer is sooner or later required to instantiate these parameters. At the current time, this instantiation activity is a matter of experience and knowledge of the SUT. This work investigates how to rationalize the instantiation of the model parameters. It is obvious that a poor instantiation may badly influence the quality of the resulting tests. However, recent results in instantiation-based theorem proving and their application to software verification show that it is often possible to guess the smallest most general data enumeration. We first provide a formal characterization of what a most general instantiation is, in the framework of functional testing. Then, we propose an approach to automate the instantiation of the model parameters, which leaves the specifier and the validation engineer free to use the desired level of abstraction, during the model design process, without having to satisfy any finiteness requirement. We investigate cases where delaying the instantiation is not a problem. This work is illustrated by a realistic running example. It is presented in the framework of the BZ-Testing-Tools methodology, which uses a B abstract machine for model-based testing and targets many implementation languages.
Electronic Notes in Theoretical Computer Science | 2004
Jean-François Couchot; Frédéric Dadeau; David Déharbe; Alain Giorgetti; Silvio Ranise
Abstract We present a technique to prove invariants of model-based specifications in a fragment of set theory. Proof obligations containing set theory constructs are translated to first-order logic with equality augmented with (an extension of) the theory of arrays with extensionality. The idea underlying the translation is that sets are represented by their characteristic function which, in turn, is encoded by an array of Booleans indexed on the elements of the set. A theorem proving procedure automating the verification of the proof obligations obtained by the translation is described. Furthermore, we discuss how a sub-formula can be extracted from a failed proof attempt and used by a model finder to build a counter-example. To be concrete, we use a B specification of a simple process scheduler on which we illustrate our technique.
Annales Des Télécommunications | 2015
Jean-François Couchot; Raphaël Couturier; Christophe Guyeux
A new steganographic method called STABYLO is introduced in this research work. Its main advantage is to be much lighter than the so-called HUGO, WOW, and UNIWARD schemes, the state of the art steganographic processes. To achieve the proposed goal, famous experimented components of signal processing, coding theory, and cryptography are combined together, leading to a scheme that can reasonably face up-to-date steganalysers.
bioinformatics and biomedicine | 2014
Bassam AlKindy; Christophe Guyeux; Jean-François Couchot; Michel Salomon; Jacques M. Bahi
In computational biology and bioinformatics, the manner to understand evolution processes within various related organisms paid a lot of attention these last decades. However, accurate methodologies are still needed to discover genes content evolution. In a previous work, two novel approaches based on sequence similarities and genes features have been proposed. More precisely, we proposed to use genes names, sequence similarities, or both, insured either from NCBI or from DOGMA annotation tools. Dogma has the advantage to be an up-to-date accurate automatic tool specifically designed for chloroplasts, whereas NCBI possesses high quality human curated genes (together with wrongly annotated ones). The key idea of the former proposal was to take the best from these two tools. However, the first proposal was limited by name variations and spelling errors on the NCBI side, leading to core trees of low quality. In this paper, these flaws are fixed by improving the comparison of NCBI and DOGMA results, and by relaxing constraints on gene names while adding a stage of post-validation on gene sequences. The two stages of similarity measures, on names and sequences, are thus proposed for sequence clustering. This improves results that can be obtained using either NCBI or DOGMA alone. Results obtained with this “quality control test” are further investigated and compared with previously released ones, on both computational and biological aspects, considering a set of 99 chloroplastic genomes.
International Journal of Bifurcation and Chaos | 2017
Sylvain Contassot-Vivier; Jean-François Couchot; Christophe Guyeux; Pierre-Cyrille Héam
Designing a pseudorandom number generator (PRNG) is a difficult and complex task. Many recent works have considered chaotic functions as the basis of built PRNGs: the quality of the output would indeed be an obvious consequence of some chaos properties. However, there is no direct reasoning that goes from chaotic functions to uniform distribution of the output. Moreover, embedding such kind of functions into a PRNG does not necessarily allow to get a chaotic output, which could be required for simulating some chaotic behaviors. In a previous work, some of the authors have proposed the idea of walking into a N-cube where a balanced Hamiltonian cycle has been removed as the basis of a chaotic PRNG. In this article, all the difficult issues observed in the previous work have been tackled. The chaotic behavior of the whole PRNG is proven. The construction of the balanced Hamiltonian cycle is theoretically and practically solved. An upper bound of the expected length of the walk to obtain a uniform distributio...