References of "Varrette, Sébastien 50003258"
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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 ▲]

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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 ▲]

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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 ▲]

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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 ▲]

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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)

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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)

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See detailPractical Security in Distributed Systems
Bertholon, Benoit UL; Cérin, Christophe; Coti, Camille et al

in Haddad, S.; Kordon, F.; Pautet, L. (Eds.) et al Distributed Systems; Design and Algorithms, 1 (2011)

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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)

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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 ▲]

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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)

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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)

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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)

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See detailUne approche génétique et source à source de l'optimisation de code
Guelton, S.; Varrette, Sébastien UL

Scientific Conference (2009, September)

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See detailDeskilling HPL - Using an Evolutionary Algorithm to Automate Cluster Benchmarking
Dunlop, Dominic UL; Varrette, Sébastien UL; Bouvry, Pascal UL

in Proc. of 8th Intl. conf. on Parallel Processing and Applied Mathematics (PPAM 2009) (2009, September), 6068(LNCS), 102--114

The High-Performance Linpack (HPL) benchmark is the ac- cepted standard for measuring the capacity of the world’s most powerful computers, which are ranked twice yearly in the Top 500 List. Since just a ... [more ▼]

The High-Performance Linpack (HPL) benchmark is the ac- cepted standard for measuring the capacity of the world’s most powerful computers, which are ranked twice yearly in the Top 500 List. Since just a small deficit in performance can cost a computer several places, it is impor- tant to tune the benchmark to obtain the best possible result. However, the adjustment of HPL’s seventeen configuration parameters to obtain maximum performance is a time-consuming task that must be performed by hand. In a previous paper, we provided a preliminary study that proposed the tuning of HPL parameters by means of an Evolutionary Algorithm. The approach was validated on a small cluster hosted at the University of Luxembourg. In this article, we extend this initial work by describing Acbea, a fully-automatic benchmark tuning tool that performs both the configuration and installation of HPL followed by an automatic search for optimized parameters that will lead to the best benchmark results. Experiments have been conducted to validate this tool on several clusters, exploiting in particular the Grid’5000 infrastructure. [less ▲]

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See detailDynamic Adaptation Applied to Sabotage Tolerance
Guelton, S.; Gautier, T.; Pazat, J.-L. et al

in Proc. of the IEEE 17th Euromicro International Conference on Parallel, Distributed, and Network-Based Processing (PDP 2009) (2009)

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See detailParallel implementation of domain decomposition algorithm for molecular dynamics
Berhe, Girma UL; Peters, Bernhard UL; Varrette, Sébastien UL et al

in PARENG 2007 (2009)

The objective of this study is to apply a domain decomposition algorithm to the La- grangian based Discrete Particle Method (DPM). The latter deals with the thermal decomposition of solid e.g. biomass ... [more ▼]

The objective of this study is to apply a domain decomposition algorithm to the La- grangian based Discrete Particle Method (DPM). The latter deals with the thermal decomposition of solid e.g. biomass fuel particles. It considers each particle as an individual entity that is represented by an instantiation of a class. Modelizing thermal conversion of biomass in real systems involves a large number of particles. This can be achieved in a reasonable computing time only through a parallel implementation able to distribute the particles e.g. objects onto the participating processors. This pa- per present such an implementation based on Orthogonal Recursive Bisection (ORB) method. Due to the fact that the particles may take arbitrary positions within the do- main, a particular issue addressed by the domain decomposition technic used in this work is to generate a load balance for each processors as uniform as possible. Fur- thermore, the particles are coupled via heat transfer. One challenge for the designed algorithm is then to identify the nearest neighbours of each particle so that the nec- essary information can be communicated between them. Since the positions of all particles are subject to change and may migrate from one processor to another, the communication links together with the number of neighbors are highly dynamic. The implementation is carried out using the KAAPI API, a C++ library for parallel pro- gramming that allows to execute ?ne/medium grain multithreaded computation with dynamic data ?ow synchronizations. First results are very promising since they indi- cate that our algorithm creates sub domains with an average imbalance ranging from 2.5% to 6.3% for uniformly distributed particles. [less ▲]

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See detailchapt. Sécurité dans les grilles de calcul,
Cérin, C.; Dubacq, J.-C.; Hérault, T. et al

in Systèmes répartis en action : de l'embarqué aux systèmes à large échelle (2008)

Detailed reference viewed: 18 (0 UL)