Description
At the Asiacrypt 2003 conference, Billet and Gilbert introduce a block cipher, which, to quote them, has the following paradoxical property: it is computationally easy to derive many equivalent distinct descriptions of the same instance of the block cipher; but it is computationally difficult, given one or even up to k of them, to recover the socalled meta-key from which they were derived, or to find any additional equivalent description, or more generally to forge any new untraceable description of the same instance of the block cipher. They exploit this property to introduce the first traceable block cipher. Their construction relies on the Isomorphism of Polynomials (IP) problem. At Eurocrypt 2006, Faugere and Perret show how to break this scheme by algebraic attack. We here strengthen the original traceable block cipher against this attack by concealing the underlying IP problems. Our modifications are such that our description of the block cipher now does not give the expected results all the time and parallel executions are used to obtain the correct value.<br/> (this work was done with Julien Bringer and Emmanuelle Dottax and will be presented - in part - at CMS'2006)
Next sessions
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Adelic reduction of module lattices
Speaker : Henry Bambury - DGA-MI et Inria Rennes
We give a strict generalisation of the LLL algorithm over number fields, based on the reduction theory of $GL(n)$ over the adele ring of a number field. Our algorithm is free of heuristics, with rigorous bounds on output quality and complexity. -- based on joint work with Seungki Kim, Changmin Lee and Phong Nguyen ---
Cryptography
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European Cyber Week: atelier cryptographie post-quantique
Dans la continuité des éditions 2021, 2022 et 2024, la DGA — en partenariat avec CREACH LABS et avec le soutien de l'ANSSI, de l'IRISA, de l'IRMAR et du Pôle d'Excellence Cyber — organise la 4e édition de l'atelier consacré à la cryptographie post-quantique dans le cadre de l'European Cyber Week 2026. Attention, il faut s'inscrire (gratuitement) au préalable — s'inscrire à la conférence Les[…] -
Post-quantum day of the cryptography seminar
A scientific day devoted to post-quantum cryptography, held in the wake of the European Cyber Week, with talks more technical than those presented at the ECW. The talks will take place at Amphi E in building 02A. To register for lunch, please do so before oct 30th using this link. -
Chiffrement homomorphe à l'aide des groupes après Nuida
Speaker : Pierre Guillot - Ravel Technologies/Université de strasbourg
Nuida et d'autres ont montré comment on peut obtenir un protocole de chiffrement pleinement homomorphe si l'on sait chiffrer les éléments d'un groupe G convenable, tout en sachant faire l'opération de G "en homomorphe". Les exemples étaient jusqu'à présent limités au chiffrement d'un bit à la fois, avec beaucoup d'opérations à effectuer pour "simuler" les portes logiques usuelles. Je vais[…]-
Cryptography
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Post-Quantum Signatures from Symmetric-Key-Friendly Techniques: From MPC-in-the-Head to VOLE-in-the-Head
Speaker : Dung Bui - Northwestern University
The MPC-in-the-Head (MPCitH) paradigm turns a secure multiparty computation protocol into a zero-knowledge proof and, via Fiat–Shamir, into a signature scheme whose security relies only on symmetric-key primitives. The framework of Katz, Kolesnikov and Wang (KKW, CCS18), which moves most of the MPC work into a committed preprocessing phase that the verifier checks by opening all-but-one of the[…] -
Nouveaux doctorants
Exposés courts des nouveaux doctorants (Elouan, Quentin, Eliot)