Antonin LEROUX

I am a part-time researcher in the team of Effective Algebraic Geometry at IRMAR, Université de Rennes. 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. For the information about my defence.

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. 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

• SCALLOP: scaling the CSI-FiSh , PKC 2023
  with L. De Feo, T. B. Fouotsa, P. Kutas, S-P. Merz, L. Panny and B. Wesolowski,
  paper
• New algorithms for the Deuring correspondence: toward practical and secure SQISign signatures , EUROCRYPT 2023
  with L. De Feo, P. Longa and B. Wesolowski,
  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

• Computation of Hilbert class polynomials and modular polynomials from supersingular elliptic curves
  paper
• Updatable Encryption from Group Actions , with M. Romeas
  paper

Presentations

• 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