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Search Results: 1 - 10 of 27102 matches for " Jean-Fran?ois Couchot "
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Steganography: a class of secure and robust algorithms
Jacques M. Bahi,Jean-Franois Couchot,Christophe Guyeux
Computer Science , 2011,
Abstract: 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.
Performance Analysis of a Keyed Hash Function based on Discrete and Chaotic Proven Iterations
Jacques M. Bahi,Jean-Franois Couchot,Christophe Guyeux
Computer Science , 2011,
Abstract: Security of information transmitted through the Internet is an international concern. This security is guaranteed by tools like hash functions. However, as security flaws have been recently identified in the current standard in this domain, new ways to hash digital media must be investigated. In this document an original keyed hash function is evaluated. It is based on chaotic iterations and thus possesses various topological properties as uniform repartition and sensibility to its initial condition. These properties make our hash function satisfy the requirements in this field. This claim is verified qualitatively and experimentally in this research work, among other things by realizing simulations of diffusion and confusion.
Steganography: a Class of Algorithms having Secure Properties
Jacques M. Bahi,Jean-Franois Couchot,Christophe Guyeux
Computer Science , 2011,
Abstract: 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 hidingalgorithms based on some finite domains iterations that are Devaney's 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.
Graph Based Reduction of Program Verification Conditions
Jean-Franois Couchot,Alain Giorgetti,Nicolas Stouls
Computer Science , 2009,
Abstract: Increasing the automaticity of proofs in deductive verification of C programs is a challenging task. When applied to industrial C programs known heuristics to generate simpler verification conditions are not efficient enough. This is mainly due to their size and a high number of irrelevant hypotheses. This work presents a strategy to reduce program verification conditions by selecting their relevant hypotheses. The relevance of a hypothesis is determined by the combination of a syntactic analysis and two graph traversals. The first graph is labeled by constants and the second one by the predicates in the axioms. The approach is applied on a benchmark arising in industrial program verification.
Application of Steganography for Anonymity through the Internet
Jacques M. Bahi,Jean-Franois Couchot,Nicolas Friot,Christophe Guyeux
Mathematics , 2012,
Abstract: In this paper, a novel steganographic scheme based on chaotic iterations is proposed. This research work takes place into the information hiding security framework. The applications for anonymity and privacy through the Internet are regarded too. To guarantee such an anonymity, it should be possible to set up a secret communication channel into a web page, being both secure and robust. To achieve this goal, we propose an information hiding scheme being stego-secure, which is the highest level of security in a well defined and studied category of attacks called "watermark-only attack". This category of attacks is the best context to study steganography-based anonymity through the Internet. The steganalysis of our steganographic process is also studied in order to show it security in a real test framework.
Class of Trustworthy Pseudo-Random Number Generators
Jacques M. Bahi,Jean-Franois Couchot,Christophe Guyeux,Qianxue Wang
Computer Science , 2011,
Abstract: With the widespread use of communication technologies, cryptosystems are therefore critical to guarantee security over open networks as the Internet. Pseudo-random number generators (PRNGs) are fundamental in cryptosystems and information hiding schemes. One of the existing chaos-based PRNGs is using chaotic iterations schemes. In prior literature, the iterate function is just the vectorial boolean negation. In this paper, we propose a method using Graph with strongly connected components as a selection criterion for chaotic iterate function. In order to face the challenge of using the proposed chaotic iterate functions in PRNG, these PRNGs are subjected to a statistical battery of tests, which is the well-known NIST in the area of cryptography.
Gene Similarity-based Approaches for Determining Core-Genes of Chloroplasts
Bassam AlKindy,Christophe Guyeux,Jean-Franois Couchot,Michel Salomon,Jacques M. Bahi
Computer Science , 2014,
Abstract: 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.
Finding the Core-Genes of Chloroplasts
Bassam AlKindy,Jean-Franois Couchot,Christophe Guyeux,Arnaud Mouly,Michel Salomon,Jacques M. Bahi
Computer Science , 2014,
Abstract: 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.
Hybrid Genetic Algorithm and Lasso Test Approach for Inferring Well Supported Phylogenetic Trees based on Subsets of Chloroplastic Core Genes
Bassam AlKindy,Christophe Guyeux,Jean-Franois Couchot,Michel Salomon,Christian Parisod,Jacques M. Bahi
Computer Science , 2015,
Abstract: The amount of completely sequenced chloroplast genomes increases rapidly every day, leading to the possibility to build large scale phylogenetic trees of plant species. Considering a subset of close plant species defined according to their chloroplasts, the phylogenetic tree that can be inferred by their core genes is not necessarily well supported, due to the possible occurrence of "problematic" genes (i.e., homoplasy, incomplete lineage sorting, horizontal gene transfers, etc.) which may blur phylogenetic signal. However, a trustworthy phylogenetic tree can still be obtained if the number of problematic genes is low, the problem being to determine the largest subset of core genes that produces the best supported tree. To discard problematic genes and due to the overwhelming number of possible combinations, we propose an hybrid approach that embeds both genetic algorithms and statistical tests. Given a set of organisms, the result is a pipeline of many stages for the production of well supported phylogenetic trees. The proposal has been applied to different cases of plant families, leading to encouraging results for these families.
An Ethnomethodological Perspective on the Conflict between Magistrates and Journalists in Cameroon  [PDF]
Jean-Franois Nguegan, Thomas Essono
Advances in Journalism and Communication (AJC) , 2015, DOI: 10.4236/ajc.2015.34013
Abstract: The report of the magistrate profession to that of a journalist in Cameroon can be studied from the perspective both of the sociology of professions and sociology of the conflict; the actors, who belong to different territories, are usually against the quality, legitimacy and competence required to deal with media information, and judicial control, individual freedom. This relationship is mainly studied in this research in terms of symbolic interactionism, to emphasize first of all on the importance that judges and journalists themselves give to their profession and secondly on the rationality of their game in the construction and the demarcation of their respective territories. This article is a contribution to the study of the discourse of these two groups of professionals who compete with each other.
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