The University of Luxembourg: A National Excellence Initiative

in Altbach, Phil; Reisberg, Liz; Salmi, Jamil (Eds.) et al Accelerated Universities: A ideas and Money Combine to Build Academic Excellence (2018)

James Bond's Most Secret Weapon

in Proceedings of the 3rd International Conference on Applications in Information Technology (2018)

This conference presents in a non-conventional way secret-key and public-key cryptology from its origins to the present days.

Hardened Bloom Filters, with an Application to Unobservability

in Annales Universitatis Mariae Curie-Skłodowska. Sectio AI, Informatica (2013), 12(4), 11-22

Classical Bloom filters may be used to elegantly check if an element e belongs to a set S, and, if not, to add e to S. They do not store any data and only provide boolean answers regarding the membership ... [more ▼]

Classical Bloom filters may be used to elegantly check if an element e belongs to a set S, and, if not, to add e to S. They do not store any data and only provide boolean answers regarding the membership of a given element in the set, with some probability of false positive answers. Bloom filters are often used in caching system to check that some requested data actually exist before doing a costly lookup to retrieve them. However, security issues may arise for some other applications where an active attacker is able to inject data crafted to degrade the filters’ algorithmic properties, resulting for instance in a Denial of Service (DoS) situation. This leads us to the concept of hardened Bloom filters, combining classical Bloom filters with cryptographic hash functions and secret nonces. We show how this approach is successfully used in the TrueNyms unobservability system and protects it against replay attacks. [less ▲]

Security and Intelligent Information Systems

Book published by Springer (2012)

Jacobians of genus 2 curves with a rational point of order 11

in Experimental Mathematics (2009), 18(1), 65-70

On the one hand, it is well-known that Jacobians of (hyper)elliptic curves defined over $\Q$ having a rational point of order $l$ can be used in many applications, for instance in the construction of ... [more ▼]

On the one hand, it is well-known that Jacobians of (hyper)elliptic curves defined over $\Q$ having a rational point of order $l$ can be used in many applications, for instance in the construction of class groups of quadratic fields with a non-trivial $l$-rank. On the other hand, it is also well-known that $11$ is the least prime number which is not the order of a rational point of an elliptic curve defined over $\Q$. It is therefore interesting to look for curves of higher genus, whose Jacobians have a rational point of order $11$. This problem has already been addressed, and Flynn found such a family $\Fl_t$ of genus $2$ curves. Now, it turns out, that the Jacobian $J_0(23)$ of the modular genus $2$ curve $X_0(23)$ has the required property, but does not belong to $\Fl_t$. The study of $X_0(23)$ leads to a method to partially solving the considered problem. Our approach allows us to recover $X_0(23)$, and to construct another $18$ distinct explicit curves of genus $2$ defined over $\Q$ and whose Jacobians have a rational point of order $11$. Of these $19$ curves, $10$ do not have any rational Weierstrass point, and $9$ have a rational Weierstrass point. None of these curves are $\Qb$-isomorphic to each other, nor $\Qb$-isomorphic to an element of Flynn's family $\Fl_t$. Finally, the Jacobians of these new curves are absolutely simple. [less ▲]

Cryptographie à Clef Publique

in Ebrahimi, Touradj; Leprévost, Franck; Warusfel, Bertrand (Eds.) Cryptographie et sécurité des systèmes et réseaux, 2 (2007)

Les briques de construction des systèmes sécurisés d'information font appel aux notions de cryptologie, qui recouvre la cryptographie (la construction de cryptosystèmes) et la cryptanalyse (la recherche ... [more ▼]

Les briques de construction des systèmes sécurisés d'information font appel aux notions de cryptologie, qui recouvre la cryptographie (la construction de cryptosystèmes) et la cryptanalyse (la recherche de failles dans les cryptosystèmes). Les cryptosystèmes reposent sur le principe de Kerckhoff, qui affirme que la sécurité d'un cryptosystème ne doit pas reposer sur l'ignorance de l'algorithme pour sa mise en œuvre, mais sur l'ignorance que l'attaquant a d'une information secrète. Ce volume, organisé en chapitres indépendants, traite de la cryptographie à clef secrète, en particulier de l'AES, et des méthodes de cryptanalyse linéaire et différentielle , de la cryptographie à clef publique, en particulier de RSA, du protocole d'échange de clefs de Diffie-Hellman, et des signatures électroniques. Il assemble ces briques de construction dans le cadre des architectures à clef publique (X.509, PGP, DNSSEC) et traite de la sécurité des systèmes (essentiellement Unix), et des réseaux. [less ▲]

Réalités de l'espionnage électronique

Book published by Lavoisier-Hermes (2006)

Cryptographie et sécurité des systèmes et réseaux

Book published by Hermès-Lavoisier (2006)

Applicative Solutions for Safe Computations in Distributed Environments

in Workshop "Trustworthy Software" (2006)

Distributed Authentication in GRID5000

in Proc. of OTM Confederated Int. Workshops on Grid Computing and its Application to Data Analysis (GADA'05) (2005, November)