Description
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.
The Program
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9:00 - 9:30
Welcome
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9:30 -10:15
Implementations of PQC on Constrained Devices
Gustavo Banegas (Inria)
Constrained devices will also need to support post-quantum cryptography (PQC). Therefore, an important question is how to integrate PQC into these devices and what impact it will have on their performance and resource consumption.
In this talk, I will discuss these challenges and present an implementation of HAETAE that achieves low stack usage across several constrained devices and microarchitectures. -
10:15 - 10:45
Coffee break
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10:45 - 11:30
A Scalable Fault Countermeasure for SLH-DSA: Trade-offs Between Memory, Performance, and Fault Resilience
Melissa Azouaoui (NXP)
Fault attacks against SLH-DSA can enable grafting tree attacks and accordingly signature forgery. This talk presents compressed caching, a scalable and parameterizable countermeasure against grafting tree fault attacks on SLH-DSA. Unlike standard caching, which entails fully caching the WOTS+ signatures and public keys, compressed caching achieves significant memory savings while maintaining strong fault detection capabilities. It can be tuned to achieve a trade-off between caching memory size, fault resilience, and performance, making it well-suited for deployment across devices with varying resource and security constraints. This talk will go over the security and performance analysis of compressed caching and show that it can be configured to achieve high fault detection probability and outperform standard caching, mainly in terms of memory but also in terms of performance.
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11:30 - 12:15
RAM and CPU efficient techniques for Falcon implementation
Thomas Pornin (NCC Group)
We present various techniques to help software implementations of the Falcon signature scheme achieve both RAM and CPU efficiency, with a particular focus on small embedded systems (Arm Cortex M4 micrcontrollers). Some of the methods allow replacing operations on floating-point (or fixed-point) values with smaller and faster operations on modular integers; moving the addition of the target vector to a later point in the processing removes the need for some FFT transforms. For the FFT itself, a novel variant is presented, which halves the number of operations, and should be generally applicable to other algorithms that use the FFT or the NTT. All the techniques are compatible with a replacement of floating-point values and operations with a fixed-point format; in total, on Arm Cortex M4, we can halve both the RAM usage and the CPU cost of signature generation.
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12:15 - 13:30
Lunch (on site)
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13:30 - 14:20
Cryptanalysis of the signature scheme Hawk
Alice Pellet-Mary (CNRS, Univ. Bordeaux)
In this talk, I will present an algorithm solving the lattice isomorphism problem in modules of rank 2 (module-LIP) over a cyclotomic number field. This algorithm reduces the underlying lattice dimension by a factor 3/4, which improves the complexity of the best known attack to solve module-LIP in these lattices (the algorithm still runs in exponential time, but with a smaller constant in the exponent).
This impacts the signature scheme Hawk, making its concrete security fall short of the NIST requirement for all security levels considered (I and V).
Finally, I will also discuss and compare with the two concurrent attacks on Hawk (by anthropic and Luo at al.). This is a joint work with Guilhem Mureau and Ludo Pulles. -
14:20 - 15:10
TBD
TBD
TBD
Practical infos
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[…] -
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)