Description
The Quantum Fourier Transform is a fundamental tool in quantum cryptanalysis, not only as the building block of Shor's algorithm, but also in attacks against symmetric cryptosystems. Indeed, hidden shift algorithms such as Simon's (FOCS 1994), which rely on the QFT, have been used to obtain attacks on some very specific block cipher structures. The Fourier Transform is also used in classical cryptanalysis, for example in FFT-based linear key-recovery attacks introduced by Collard et al. (ICISC 2007). Whether such techniques can be adapted to the quantum setting has remained so far an open question. In this talk, we will present a new framework for quantum linear key-recovery attacks using the QFT. These attacks loosely follow the classical method of Collard et al., but adapt it to the quantum setting. Classically, the FFT-based attack needs to compute a statistic (experimental correlation) which is higher for a good key guess, and lower for wrong guesses. The quantum attack encodes this statistic in the amplitudes of a quantum state. On some conditions, this can be used to devise new quantum key-recovery attacks which may be applicable to a broader class of ciphers.
Prochains exposés
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Adelic reduction of module lattices
Orateur : 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.