Description
After the publication of Shor's algorithm, it became evident the most popular public-key cryptographic systems that rely on the integer factorization problem or on the discrete logarithm problem would be easily solvable using large enough quantum computers (if such quantum computers are ever built). That triggered a vivid interest in the research of cryptographic algorithms (mostly public-key cryptographic systems) that are resistant to quantum computers. There are several approaches for designing post-quantum public key algorithms. The main candidates Hash-Based signatures, are Multivariate cryptosystems, Code-based cryptosystems and Lattice-based cryptosystems.<br/> Although Multivariate, Code-based and Lattice-based Cryptosystems rely on different algebraic problems, the goal of this talk is to show that Gr\"obner bases, via algebraic attacks, is a common tool which is underlying the security of these post-quantum public-key algorithms. As such, Gröbner bases is then a fundamental tool to design and analyze public-key schemes in the post-quantum era. In the talk, we will describe two applications. First, an efficient attack against a quantum money scheme proposed at STOC'12 whose security is based on a variant of the Isomorphism of Polynomial. This is [1] a joint work with Marta Conde, and Jean-Charles Faugère. Secondly, we will also show that Gröbner Bases can be used to analyze the security of the Learning With Errors (LWE) problem. Arora and Ge proved few years ago that LWE can be solved by linearizing a system of algebraic equations. We will describe a refined complexity analysis for solving Arora-Ge-style systems of non-linear equations with Gröbner bases for LWE and a variant of LWE BinaryError-LWE. This is [2] a joint work with Martin Albrecht, Carlos Cid, Jean-Charles Faugère, and Robert Fitzpatrick.<br/> [1] Marta Conde Pena, Jean-Charles Faugère, Ludovic Perret. Algebraic Cryptanalysis of a Quantum Money Scheme The Noise-Free Case. PKC'15. [2] Martin R. Albrecht, Carlos Cid, Jean-Charles Faugère, Robert Fitzpatrick, Ludovic Perret. Algebraic Algorithms for LWE Problems. IACR Cryptology ePrint Archive 2014: 1018 (2014).
Next sessions
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Cyclotomic Cosets: Hidden Subgroup and Quantum Sieving Algorithm for Prime-Power Moduli
Speaker : Mathias Boucher - Université de Rennes
The Dihedral Coset Problem (DCP), also known as the hidden shift problem, plays a fundamental role in post-quantum public-key cryptography, since the Learning-With-Error problem reduces to DCP. The “Simon meets Kuperberg” quantum algorithm by Bonnetain and Naya-Plasencia solves the DCP in quasi-polynomial time when the modulus is a power of two. We provide a generalization of this algorithm for[…] -
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)