References of "Varrette, Sébastien 50003258"
     in
Bookmark and Share    
Full Text
See detailUsing Data-flow analysis in MAS for power-aware HPC runs
Varrette, Sébastien UL; Danoy, Grégoire UL; Guzek, Mateusz UL et al

in Proc. of the IEEE Intl. Conf. on High Performance Computing and Simulation (HPCS'13) (2013)

Detailed reference viewed: 150 (8 UL)
Full Text
Peer Reviewed
See detailJShadObf: A JavaScript Obfuscator Based on Multi-Objective Optimization Algorithms
Bertholon, Benoit UL; Varrette, Sébastien UL; Bouvry, Pascal UL

in Lopez, Javier; Huang, Xinyi; Sandhu, Ravi (Eds.) Network and System Security (2013)

Detailed reference viewed: 267 (5 UL)
Full Text
Peer Reviewed
See detailShadObf: A C-Source Obfuscator Based on Multi-objective Optimisation Algorithms
Bertholon, Benoit UL; Varrette, Sebastien UL; Martinez, Sebastien

in Proceedings of the 2013 IEEE 27th International Symposium on Parallel and Distributed Processing Workshops and PhD Forum (2013)

Detailed reference viewed: 168 (4 UL)
Full Text
Peer Reviewed
See detailExpected Running Time of Parallel Evolutionary Algorithms on Unimodal Pseudo-Boolean Functions over Small-World Networks
Muszynski, Jakub UL; Varrette, Sébastien UL; Bouvry, Pascal UL

in Proc. of the IEEE Congress on Evolutionary Computation (CEC'2013) (2013)

This paper proposes a theoretical and experimental analysis of the expected running time for an elitist parallel Evolutionary Algorithm (pEA) based on an island model executed over small-world networks ... [more ▼]

This paper proposes a theoretical and experimental analysis of the expected running time for an elitist parallel Evolutionary Algorithm (pEA) based on an island model executed over small-world networks. Our study assumes the resolution of optimization problems based on unimodal pseudo-boolean funtions. In particular, for such function with d values, we improve the previous asymptotic upper bound for the expected parallel running time from O(d√n) to O(d log n). This study is a first step towards the analysis of influence of more complex network topologies (like random graphs created by P2P networks) on the runtime of pEAs. A concrete implementation of the analysed algorithm have been performed on top of the ParadisEO framework and run on the HPC platform of the University of Luxembourg (UL). Our experiments confirm the expected speed- up demonstrated in this article and prove the benefit that pEA can gain from a small-world network topology. [less ▲]

Detailed reference viewed: 108 (1 UL)
Full Text
Peer Reviewed
See detailA Holistic Model of the Performance and the Energy-Efficiency of Hypervisors in an HPC Environment
Guzek, Mateusz UL; Varrette, Sébastien UL; Plugaru, Valentin UL et al

in Energy Efficiency in Large Scale Distributed Systems (2013)

Detailed reference viewed: 131 (7 UL)
Full Text
Peer Reviewed
See detailHash function generation by means of Gene Expression Programming
Varrette, Sébastien UL; Muszynski, Jakub UL; Bouvry, Pascal UL

in Intl. Conf. on Cryptography and Security System (CSS’12) (2012, September), XII(3), 37-53

Cryptographic hash functions are fundamental primitives in modern cryptography and have many security applications (data integrity checking, cryptographic protocols, digital signatures, pseudo random ... [more ▼]

Cryptographic hash functions are fundamental primitives in modern cryptography and have many security applications (data integrity checking, cryptographic protocols, digital signatures, pseudo random number generators etc.). At the same time novel hash functions are designed (for instance in the framework of the SHA-3 contest organized by the National Institute of Standards and Technology (NIST)), the cryptanalysts exhibit a set of statistical metrics (propagation criterion, frequency analysis etc.) able to assert the quality of new proposals. Also, rules to design "good" hash functions are now known and are followed in every reasonable proposal of a new hash scheme. This article investigates the ways to build on this experiment and those metrics to generate automatically compression functions by means of Evolutionary Algorithms (EAs). Such functions are at the heart of the construction of iterative hash schemes and it is therefore crucial for them to hold good properties. Actually, the idea to use nature-inspired heuristics for the design of such cryptographic primitives is not new: this approach has been successfully applied in several previous works, typically using the Genetic Programming (GP) heuristic [1]. Here, we exploit a hybrid meta-heuristic for the evolutionary process called Gene Expression Programming (GEP) [2] that appeared far more e?cient computationally speaking compared to the GP paradigm used in the previous papers. In this context, the GEPHashSearch framework is presented. As it is still a work in progress, this article focuses on the design aspects of this framework (individuals de?nitions, ?tness objectives etc.) rather than on complete implementation details and validation results. Note that we propose to tackle the generation of compression functions as a multi-objective optimization problem in order to identify the Pareto front i.e. the set of non-dominated functions over the four ?tness criteria considered. If this goal is not yet reached, the ?rst experimental results in a mono-objective context are promising and open the perspective of fruitful contributions to the cryptographic community [less ▲]

Detailed reference viewed: 155 (1 UL)
Full Text
Peer Reviewed
See detailConvergence Analysis of Evolutionary Algorithms in the Presence of Crash-Faults and Cheaters
Muszynski, Jakub UL; Varrette, Sébastien UL; Bouvry, Pascal UL et al

in Computers & Mathematics with Applications (2012), 64(12), 3805-3819

This paper analyzes the fault-tolerance nature of Evolutionary Algorithms (EAs) when executed in a distributed environment subjected to malicious acts. More precisely, the inherent resilience of EAs ... [more ▼]

This paper analyzes the fault-tolerance nature of Evolutionary Algorithms (EAs) when executed in a distributed environment subjected to malicious acts. More precisely, the inherent resilience of EAs against two types of failures is considered: (1) crash faults, typically due to resource volatility which lead to data loss and part of the computation loss; (2) cheating faults, a far more complex kind of fault that can be modeled as the alteration of output values produced by some or all tasks of the program being executed. This last type of failure is due to the presence of cheaters on the computing platform. Most often in Global Computing (GC) systems such as BOINC, cheaters are attracted by the various incentives provided to stimulate the volunteers to share their computing resources: cheaters typically seek to obtain rewards with little or no contribution to the system. In this paper, the Algorithm-Based Fault Tolerance (ABFT) aspects of EAs against the above types of faults is characterized. Whereas the inherent resilience of EAs has been previously observed in the literature, for the first time, a formal analysis of the impact of the considered faults over the executed EA including a proof of convergence is proposed in this article. By the variety of problems addressed by EAs, this study will hopefully promote their usage in the future developments around distributed computing platform such as Desktop Grids and Volunteer Computing Systems or Cloud systems where the resources cannot be fully trusted. [less ▲]

Detailed reference viewed: 106 (0 UL)
Full Text
Peer Reviewed
See detailCERTICLOUD, une plate-forme Cloud IaaS sécurisée
Bertholon, Benoit UL; Varrette, Sébastien UL; Bouvry, Pascal UL

in Technique et Science Informatiques (2012), 31(8-9-10), 1121-1152

The security issues raised by the Cloud paradigm are not always tackled from the user point of view. For instance, considering an Infrastructure-as-a-Service (IaaS) Cloud, it is currently impossible for a ... [more ▼]

The security issues raised by the Cloud paradigm are not always tackled from the user point of view. For instance, considering an Infrastructure-as-a-Service (IaaS) Cloud, it is currently impossible for a user to certify in a reliable and secure way that the environment he deployed (typically a Virtual Machine (VM)) has not been corrupted, whether by malicious acts or not. Yet having this functionality would enhance the confidence on the IaaS provider and therefore attract new customers. This paper fills this need by proposing CERTICLOUD, a novel approach for the protection of IaaS platforms that relies on the concepts developed in the Trusted Computing Group (TCG) together with hardware elements, i.e., Trusted Platform Module (TPM) to offer a secured and reassuring environment. Those aspects are guaranteed by two protocols : TCRR and VerifyMyVM. When the first one asserts the integrity of a remote resource and permits to exchange a private symmetric key, the second authorizes the user to detect trustfully and on demand any tampering attempt on his running VM. These protocols being key components in the proposed framework, we take very seriously their analysis against known cryptanalytic attacks. This is testified by their successful validation by AVISPA and Scyther, two reference tools for the automatic verification of security protocols. The CERTICLOUD proposal is then detailed : relying on the above protocols, this platform provides the secure storage of users environments and their safe deployment onto a virtualization framework. While the physical resources are checked by TCRR, the user can execute on demand the VerifyMyVM protocol to verify the integrity of his deployed environment. Experimental results operated on a first prototype of CERTICLOUD over Nimbus demonstrate the feasibility and the low overhead of the approach, together with its easy implementation on recent commodity machines. [less ▲]

Detailed reference viewed: 130 (4 UL)
Full Text
Peer Reviewed
See detailEnergy Efficiency on Scalable Computing Architectures
Barrios Hernandez, C. J.; Sierra, Daniel A.; Varrette, Sébastien UL et al

in 11th IEEE Intl. Conf. on Computer and Information Technology (CIT’11) (2011, October)

Nowadays, power consumption in computer systems is an active and important subject of discussion in both research and political communities. Indeed, increasing the performance of such computer systems ... [more ▼]

Nowadays, power consumption in computer systems is an active and important subject of discussion in both research and political communities. Indeed, increasing the performance of such computer systems frequently requires increasing the number of resources, thus leading to higher power consumption and a negative impact on the environment. Some strategies to reduce the energy consumption are based on hardware modifications, the usage of energy-aware software and new rules of computation resources utilization. This paper analyzes the energy consumption of HPC platforms and Grid computing infrastructures from two different perspectives: (i) cost in energy due to idle/active status and (ii) cost in energy due to data transfer. [less ▲]

Detailed reference viewed: 218 (1 UL)
Full Text
Peer Reviewed
See detailCertiCloud: a Novel TPM-based Approach to Ensure Cloud IaaS Security
Bertholon, Benoit UL; Varrette, Sébastien UL; Bouvry, Pascal UL

in 4th IEEE Intl. Conf. on Cloud Computing (CLOUD 2011) (2011, July)

The security issues raised by the Cloud paradigm are not always tackled from the user point of view. For instance, considering an Infrastructure-as-a-Service (IaaS) Cloud, it is currently impossible for a ... [more ▼]

The security issues raised by the Cloud paradigm are not always tackled from the user point of view. For instance, considering an Infrastructure-as-a-Service (IaaS) Cloud, it is currently impossible for a user to certify in a reliable and secure way that the environment he deployed (typically a Virtual Machine(VM)) has not been corrupted, whether by malicious acts or not. Yet having this functionality would enhance the confidence on the IaaS provider and therefore attract new customers. This paper fills this need by proposing CERTICLOUD, a novel approach for the protection of IaaS platforms that relies on the concepts developed in the Trusted Computing Group (TCG) together with hardware elements, i.e., Trusted Platform Module (TPM) to offer a secured and reassuring environment. Those aspects are guaranteed by two protocols: TCRR and Verify MyVM. When the first one asserts the integrity of a remote resource and permits to exchange a private symmetric key, the second authorizes the user to detect trustfully and on demand any tampering attempt on its running VM. These protocols being key components in the proposed framework, we take very seriously their analysis against known cryptanalytic attacks. This is testified by their successful validation by AVISPA and Scyther, two reference tools for the automatic verification of security protocols. The CERTICLOUD proposal is then detailed: relying on the above protocols, this platform provides the secure storage of users environments and their safe deployment onto a virtualization framework. While the physical resources are checked by TCRR, the user can execute on demand the Verify MyVM protocol to certify the integrity of its deployed environment. Experimental results operated on a first prototype of CERTICLOUD demonstrate the feasibility and the low overhead of the approach, together with its easy implementation on recent commodity machines. [less ▲]

Detailed reference viewed: 122 (5 UL)
Full Text
Peer Reviewed
See detailA Signature Scheme for Distributed Executions based on Control flow Analysis..
Varrette, Sébastien UL; Bertholon, Benoit UL; Bouvry, Pascal UL

in 19th Intl. conference on Security and Intelligent Information Systems (SIIS 2011) (2011, June)

Detailed reference viewed: 102 (0 UL)
Full Text
Peer Reviewed
See detailCertiCloud: une plate-forme Cloud IaaS sécurisée
Bertholon, Benoit UL; Varrette, Sébastien UL; Bouvry, Pascal UL

in RenPar'20 2011 (2011)

La sécurité des Clouds est un aspect essentiel qui n'est pas forcément abordé selon le point de vue de l'utilisateur. En particulier, sur une plate-forme de type IaaS, il est actuellement impossible pour ... [more ▼]

La sécurité des Clouds est un aspect essentiel qui n'est pas forcément abordé selon le point de vue de l'utilisateur. En particulier, sur une plate-forme de type IaaS, il est actuellement impossible pour un utilisateur de certifier de manière fiable et sécurisée que l'environnement qu'il a déployé (typiquement sous forme d'une machine virtuelle) est toujours dans un état qu'il juge intègre et opérationnel. Cet article s'attelle à cette tâche en proposant CertiCloud, une plate-forme Cloud de type IaaS qui exploite les concepts développés dans le cadre du TCG mais aussi les éléments matériels que sont les TPM pour offrir à l'utilisateur un environnement sécurisé et sécurisant. Ces deux aspects sont garantis par les deux protocoles TCRR et VerifMyVM qui sont à la base de CertiCloud. Quand le premier permet de certifier l'intégrité d'une machine distante et d'échanger une clef de chiffrement symétrique, le second permet à l'utilisateur de s'assurer dynamiquement et à la demande de l'intégrité de sa machine virtuelle exécutée sur les ressources de \CertiC. Ces deux protocoles étant les briques de base de notre plate-forme, une attention toute particulière a été apportée à leurs élaborations. A cet effet, ils ont été validés avec succès par AVISPA et Scyther, deux outils de référence dans le domaine de la vérification automatique des protocoles de sécurité (cette analyse est présentée dans cet article). Ensuite, la plate-forme CertiCloud est détaillée: outre les protocoles TCRR et VerifMyVM, elle propose le stockage sécurisé des environnements utilisateurs et leurs exécutions à travers un framework de virtualisation reprenant l'hyperviseur Xen. Quand les ressources physiques sont certifiées par TCRR, l'utilisateur peut utiliser à la demande le protocole VerifMyVM pour s'assurer de l'intégrité de son environnement déployé. Un prototype de CertiCloud a été réalisé et nous présentons les premiers résultats expérimentaux qui démontrent de la faisabilité et du faible surcoût de notre approche sur des scénarios classiquement rencontrés sur les infrastructures Cloud de type IaaS. [less ▲]

Detailed reference viewed: 110 (5 UL)
Full Text
Peer Reviewed
See detailA Signature Scheme for Distributed Executions based on Control flow Analysis.
Bertholon, Benoit UL; Varrette, Sébastien UL; Bouvry, Pascal UL

in Proc. of the 19th Intl. conference on Security and Intelligent Information Systems (SIIS 2011) (2011)

Detailed reference viewed: 122 (3 UL)
Peer Reviewed
See detailchap. "Practical Security in Distributed Systems"
Bertholon, Benoit UL; Cérin, C.; Coti, C. et al

in Distributed Systems (volume 1); Design and Algorithms (2011)

Detailed reference viewed: 52 (3 UL)
Full Text
Peer Reviewed
See detailOn the Resilience of [distributed] Evolutionary Algorithms against Cheaters in Global Computing Platforms
Varrette, Sébastien UL; Tantar, Emilia UL; Bouvry, Pascal UL

in Proc. of the 14th Intl. Workshop on Nature Inspired Distributed Computing (NIDISC 2011), part of the 25th IEEE/ACM Intl. Parallel and Distributed Processing Symposium (IPDPS 2011) (2011)

Detailed reference viewed: 98 (1 UL)
Full Text
Peer Reviewed
See detailCheating impact on distributed Evolutionary Algorithms over BOINC computations.
Varrette, Sébastien UL; Muszynski, Jakub UL; Bouvry, Pascal UL

in n Proc. of the 19th Intl. conference on Security and Intelligent Information Systems (SIIS 2011) (2011)

Detailed reference viewed: 89 (2 UL)
Full Text
Peer Reviewed
See detailOn the Resilience of [Distributed] EAs against Cheaters in Global Computing Platforms
Varrette, Sébastien UL; Tantar, Emilia UL; Bouvry, Pascal UL

in 25th IEEE International Symposium on Parallel and Distributed Processing (IPDPS 2011) (2011)

Detailed reference viewed: 107 (2 UL)