Antonin LEROUX

I am a researcher in the team of Effective Algebraic Geometry at IRMAR, Université de Rennes and a cryptographic expert at DGA-MI. Before that, I was a PhD student in the team GRACE at Ecole Polytechnique and INRIA Saclay under the supervision of Luca de Feo and Benjamin Smith.

I focus my research on isogeny-based cryptography. My main interest is on Quaternion Algebras and their impact on isogenies through the Deuring correspondence. This equivalence of categories between geometric objects that are elliptic curves and algebraic quaternion have showed to be a powerful tool to analyze the security of isogeny-based scheme. It has also some constructive applications such as signature. SQIsign, the main construction we obtained with this techniques was recently submitted to the NIST PQC competition new call for signatures. All the information on the submission are available here.

More generally, I am interested in everything related to isogeny-based cryptography and the algorithmic challenges it raises. I have also done some work on improving the efficiency of isogenies' evaluation, check it out at velusqrt.isogeny.org.
I am interested in cryptography in general and also done some work in Multiparty Computation.

The manuscript of my thesis is available here.

Publications

• Computing Orientations from the Endomorphism Ring of Supersingular Curves and Applications , with J. K. Eriksen
  CiC
  paper
• SQIsign2D-West, The Fast, the Small, and the Safer , with A. Basso, P. Dartois, L. De Feo, L. Maino, G. Pope, D. Robert and B. Wesolowski
  ASIACRYPT 2024
  paper
• SQIsignHD : New Dimensions in Cryptography , with P. Dartois, D. Robert and B. Wesolowski
  EUROCRYPT 2024, Best Paper Award
  paper
• Updatable Encryption from Group Actions , with M. Romeas
  PQC 2024
  paper
• SCALLOP-HD: group action from 2-dimensional isogenies , with M. Chen, and L. Panny
  PKC 2024
  paper
• Hidden Stabilizers, the Isogeny To Endomorphism Ring Problem and the Cryptanalysis of pSIDH, with M. Chen, M. Imran, G. Ivanyos, P. Kutas and C. Petit
  ASIACRYPT 2023
  paper
• SCALLOP: scaling the CSI-FiSh, with L. De Feo, T. B. Fouotsa, P. Kutas, S-P. Merz, L. Panny and B. Wesolowski,
  PKC 2023
  paper
• New algorithms for the Deuring correspondence: toward practical and secure SQISign signatures, with L. De Feo, P. Longa and B. Wesolowski,
  EUROCRYPT 2023
  paper
• A new isogeny representation and applications to cryptography,
  ASIACRYPT 2022
  paper
• An effective lower bound on the number of orientable supersingular elliptic curves,
  SAC 2022
  paper
• Communication-Efficient Proactive MPC for Dynamic Groups with Dishonest Majorities, with K. Eldefrawy and T. Lepoint
  ACNS 2022
  paper
• SÉTA: Supersingular Encryption from Torsion Attacks, with L. De Feo and C. Delpech de Saint Guilhem and T. B. Fouotsa and P. Kutas and C. Petit and J. Silva and B. Wesolowski
  ASIACRYPT 2021
  paper
• SQIsign: Compact Post-Quantum Signatures from Quaternions and Isogenies, , with L. de Feo, D. Kohel, C. Petit and B. Wesolowski
  ASIACRYPT 2020, Best Paper Award
  paper
• Faster computation of isogenies of large prime degree , with D. J. Bernstein, L. de Feo and B. Smith
  Fourteenth Algorithmic Number Theory Symposium, 2020
  website paper presentation
• Communication-Efficient Proactive Secret Sharing for Dynamic Groups with Dishonest Majorities, with K. Eldefrawy and T. Lepoint
  ACNS 2020
  paper
• Inducing Readable Oblique Decision Trees, with M. Boussard and R. Des
  ICTAI 2018
  paper

Preprints

• Erebor and Durian: Full Anonymous Ring Signatures from Quaternions and Isogenies, with G. Borin and Y-F. Lai
  paper
• Verifiable random function from the Deuring correspondence and higher dimensional isogenies
  paper
• Computation of Hilbert class polynomials and modular polynomials from supersingular elliptic curves
  paper

Presentations

• SQIsign2D-West: the fast, the small, and the safer, 05/07/2024, Séminaire C2, Paris
• Verifiable random function from the Deuring correspondence and higher dimensional isogenies, 17/11/2023, KULB seminar, Leuven slides
• SQIsign: Short Quaternion and Isogeny signature, 27/09/2023, talk at Oxford PQ Workshop
• SQIsign: Short Quaternion and Isogeny signature, 29/06/2023, talk at Journée PEPR PQ-TLS slides
• New algorithms for the Deuring correspondence: toward practical and secure SQIsign signatures, 26/04/2023, talk at EUROCRYPT, 2023
• A new algorithm for the effective Deuring correspondence: making SQISign faster,
  25/10/2022, talk at the Isogeny club.
• An overview of the Deuring correspondence and isogeny-based cryptography,
  14/10/2022, talk at the Séminaire crypto de Rennes
• The Deuring Correspondence and Isogeny-based cryptography: SQISign and new Security Problems,
  11/12/2021, talk at the International Workshop on Post-Quantum Cryptography slides
• SETA: Supersingular Encryption from Torsion Attack,
  Talk at GT-c2, November 2021 slides
• SETA: Supersingular Encryption from Torsion Attack,
  Video for ASIACRYPT 2021, video
• SQISign: Compact Post-Quantum from Quaternions and Isogenies,
  Talk for ASIACRYPT 2020 at the best paper award session, video
• Communication-Efficient Proactive Secret Sharing for Dynamic Groups with Dishonest Majorities,
  Video for ACNS 2020 video
• Faster Computation of isogenies of large prime degree,
  Fourteenth Algorithmic Number Theory Symposium, 2020 video
• The Generalized Quaternion Isogeny Path Problem,
  03/04/2020, talk at Séminaire de cryptographie de l'université de Rennes 1 slides
• The Generalized KLPT Algorithm,
  30/01/2020, talk at Séminaire ATI de l'Université de Marseille slides

Reviews
Program member for:

• ACNS 2025

• EUROCRYPT 2025
• Nutmic 2024
• ASIACRYPT 2023
• PKC 2023
• EUROCRYPT 2022
• CRYPTO 2021
• CRYPTO 2020

Journal of Algebra, MathComp, Finite Fields and their Applications, IEEE transactions on Information theory, Design Codes and Cryptography, Journal of Cryptographic engineering, IEEE transactions on Information Forensics and Security