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Accueil > Pages Perso > Carlos Aguilar

Carlos Aguilar

IE Temporaire sur CDD -  UNS

Dernières publicationsHAL

pour l'idHal "carlos-aguilar" :

titre
XPIR : Private Information Retrieval for Everyone
auteur
Carlos Aguilar Melchor, Joris Barrier, Laurent Fousse, Marc-Olivier Killijian
article
Proceedings on Privacy Enhancing Technologies, De Gruyter Open, 2016, 2016, pp.155-174. 〈10.1515/popets-2016-0010〉
annee_publi
2016
resume
A Private Information Retrieval (PIR) scheme is a protocol in which a user retrieves a record from a database while hiding which from the database administrators. PIR can be achieved using mutually-distrustful replicated databases, trusted hardware, or cryptography. In this paper we focus on the later setting which is known as single-database computationally-Private Information Retrieval (cPIR). Classic cPIR protocols require that the database server executes an algorithm over all the database content at very low speeds which impairs their usage. In [1], given certain assumptions , realistic at the time, Sion and Carbunar showed that cPIR schemes were not practical and most likely would never be. To this day, this conclusion is widely accepted by researchers and practitioners. Using the paradigm shift introduced by lattice-based cryptography , we show that the conclusion of Sion and Carbunar is not valid anymore: cPIR is of practical value. This is achieved without compromising security, using standard crytosystems, and conservative parameter choices.
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titre
P–T–t–d evolution of orogenic middle crust of the Roc de Frausa Massif (Eastern Pyrenees): A result of horizontal crustal flow and Carboniferous doming.
auteur
Carlos Aguilar Melchor, M Liesa,, P. ŠtÍpskÁ, Karel Schulmann, J-A Muñoz,, J.M Casas,
article
Journal of Metamorphic Geology, Wiley-Blackwell, 2015, 33, pp.273-294
annee_publi
2015
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titre
P–T–t–d evolution of orogenic middle crust of the Roc de Frausa Massif (Eastern Pyrenees): A result of horizontal crustal flow and Carboniferous doming?
auteur
Carlos Aguilar Melchor, M Liesa, P. ŠtÍpskÁ, Karel Schulmann, J.A Munoz,, J.M Casas,
article
Journal of Metamorphic Geology, Wiley-Blackwell, 2015, 33, pp.273-294. 〈10.1111/jmg.12120〉
annee_publi
2015
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titre
Sealing the Leak on Classical NTRU Signatures
auteur
Carlos Aguilar Melchor, Xavier Boyen, Jean-Christophe Deneuville, Philippe Gaborit
article
Lecture Notes in Computer Science. 6th International Workshop, PQCrypto 2014, Oct 2014, Waterloo, Canada. springer, 8772, pp.1-21, 2014, Post-Quantum Cryptography. 〈10.1007/978-3-319-11659-4_1〉
annee_publi
2014
resume
Initial attempts to obtain lattice based signatures were closely related to reducing a vector modulo the fundamental parallelepiped of a secret basis (like GGH [9], or NTRUSign [12]). This approach leaked some information on the secret, namely the shape of the parallelepiped, which has been exploited on practical attacks [24]. NTRUSign was an extremely efficient scheme, and thus there has been a noticeable interest on developing countermeasures to the attacks, but with little success [6]. In [8] Gentry, Peikert and Vaikuntanathan proposed a randomized version of Babai’s nearest plane algorithm such that the distribution of a reduced vector modulo a secret parallelepiped only depended on the size of the base used. Using this algorithm and generating large, close to uniform, public keys they managed to get provably secure GGH-like lattice-based signatures. Recently, Stehlé and Steinfeld obtained a provably secure scheme very close to NTRUSign [26] (from a theoretical point of view). In this paper we present an alternative approach to seal the leak of NTRUSign. Instead of modifying the lattices and algorithms used, we do a classic leaky NTRUSign signature and hide it with gaussian noise using techniques present in Lyubashevky’s signatures. Our main contributions are thus a set of strong NTRUSign parameters, obtained by taking into account latest known attacks against the scheme, a statistical way to hide the leaky NTRU signature so that this particular instantiation of CVP-based signature scheme becomes zero-knowledge and secure against forgeries, based on the worst-case hardness of the O~(N1.5) -Shortest Independent Vector Problem over NTRU lattices. Finally, we give a set of concrete parameters to gauge the efficiency of the obtained signature scheme.
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titre
Jean-Christophe Deneuville - Sealing the Leak on classical GGH and NTRU signatures
auteur
Jean-Christophe Deneuville, Carlos Aguilar Melchor, Xavier Boyen, Philippe Gaborit, Fanny Bastien
article
2014
annee_publi
2014
resume
Sealing the Leak on classical GGH and NTRU signatures
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titre
A Code-Based Undeniable Signature Scheme
auteur
Carlos Aguilar Melchor, Slim Bettaieb, Philippe Gaborit, Julien Schreck
article
Martijn Stam. 14th IMA International Conference, IMACC 2013., Dec 2013, Oxford, United Kingdom. Springer Berlin Heidelberg, 8308, pp.99-119, 2013, Lecture Notes in Computer Science. 〈10.1007/978-3-642-45239-0_7〉
annee_publi
2013
resume
In this work we propose the first code-based undeniable signature scheme (and more generally the first post-quantum undeniable signature scheme). The verification protocols for our scheme are 3-pass zero-knowledge protocols derived from the Stern authentication protocol. There are two main ideas in our protocol, first we remark that it is possible to obtain a full-time undeniable signature from a one-time undeniable signature simply by signing the one-time public key by a standard signature. Second, we introduce a zero-knowledge variation on the Stern authentication scheme which permits to prove that one or two different syndromes are associated (or not) to the same low weight word. We give a polynomial reduction of the security of our scheme to the security of the syndrome decoding problem.
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titre
Towards practical program execution over fully homomorphic encryption schemes
auteur
Simon Fau, Renaud Sirdey, Caroline Fontaine, Carlos Aguilar Melchor, Guy Gogniat
article
2013 Eighth International Conference on P2P, Parallel, Grid, Cloud and Internet Computing (3PGCIC-2013), Oct 2013, Compiègne, France. 2013
annee_publi
2013
resume
This paper intends to provide a first assessment of the practicality of using Fully Homomorphic Encryption (FHE) to perform real calculations, in terms of software engineering as well as performances. We present a prototype of a compilation and execution infrastructure targeting any FHE scheme. The paper also provides some preliminary experimental results obtained with our implementation of the Brakerski-Gentry-Vaikuntanathan (BGV) scheme, which is one of the most promising FHE scheme with respect to practicality.
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titre
Adapting Lyubashevsky's Signature Schemes to the Ring Signature Setting
auteur
Carlos Aguilar Melchor, Slim Bettaieb, Xavier Boyen, Laurent Fousse, Philippe Gaborit
article
Amr Youssef, Abderrahmane Nitaj, Aboul Ella Hassanien. 6th International Conference on Cryptology in Africa, Jun 2013, Cairo, Egypt. Springer Berlin Heidelberg, 7918, pp.1-25, 2013, Lecture Notes in Computer Science. 〈10.1007/978-3-642-38553-7_1〉
annee_publi
2013
resume
Basing signature schemes on strong lattice problems has been a long standing open issue. Today, two families of lattice-based signature schemes are known: the ones based on the hash-and-sign construction of Gentry et al.; and Lyubashevsky's schemes, which are based on the Fiat-Shamir framework. In this paper we show for the first time how to adapt the schemes of Lyubashevsky to the ring signature setting. In particular we transform the scheme of ASIACRYPT 2009 into a ring signature scheme that provides strong properties of security under the random oracle model. Anonymity is ensured in the sense that signatures of different users are within negligible statistical distance even under full key exposure. In fact, the scheme satisfies a notion which is stronger than the classical full key exposure setting as even if the keypair of the signing user is adversarially chosen, the statistical distance between signatures of different users remains negligible. Considering unforgeability, the best lattice-based ring signature schemes provide either unforgeability against arbitrary chosen subring attacks or insider corruption in log-sized rings. In this paper we present two variants of our scheme. In the basic one, unforgeability is ensured in those two settings. Increasing signature and key sizes by a factor k (typically 80 − 100), we provide a variant in which unforgeability is ensured against insider corruption attacks for arbitrary rings. The technique used is pretty general and can be adapted to other existing schemes.
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titre
Recent advances in homomorphic encryption: a possible future for signal processing in the encrypted domain
auteur
Carlos Aguilar Melchor, Simon Fau, Caroline Fontaine, Guy Gogniat, Renaud Sirdey
article
Special Issue: Signal Processing in the Encrypted Domain, IEEE Signal Processing Magazine, 2013, pp.108-107
annee_publi
2013
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titre
LE CHIFFREMENT HOMOMORPHE OU COMMENT EFFECTUER DES TRAITEMENTS SUR DES DONNÉES CHIFFRÉES
auteur
Carlos Aguilar Melchor, Marc Rybowicz
article
Article de vulgarisation scientifique. 2012
annee_publi
2012
resume
Et si vos données n'étaient jamais déchiffrées, même en mémoire, même quand vos applications ou le système d'exploitation les utilise ? Le chiffrement dit " complètement homomorphe " permettrait de réaliser de tels exploits. Seul hic, la construction d'un tel système de chiffrement est restée pendant trente ans un problème ouvert,...
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