About me

I am currently an ANSSI-Inria postdoc in Mathematics and Cryptography, in the GRACE team at Inria Saclay. I obtained my PhD from Sorbonne Université in 2022 under the supervision of David Madore and Fabrice Orgogozo. From 2022 to 2024, I was a postdoc in the C² team at Télécom Paris.

Research

My research focuses on the interplay between cryptography, arithmetic geometry, and coding theory.

Explicit Euclidean division algorithms for some degree 8 number rings
Christophe Levrat [recently submitted]
 [ arXiv | SageMath code ]
Effective Artin–Schreier–Witt theory for curves
Christophe Levrat, Rubén Muñoz--Bertrand [recently submitted]
 [ arXiv | SageMath code by Rubén ]
Highway to Hull: A New Algorithm for Solving the Matrix Code Equivalence Problem
Alain Couvreur, Christophe Levrat [Advances in Cryptology -- CRYPTO 2025]
 [ arXiv | eprint | published version ]
A Divide-and-Conquer Sumcheck Protocol
Christophe Levrat, Tanguy Medevielle, Jade Nardi [IACR Communications in Cryptology, 2025]
 [ arXiv | eprint | published version ]
Computing the cohomology of constructible étale sheaves on curves
Christophe Levrat [Journal de Théorie des Nombres de Bordeaux, 2024]
 [ arXiv | published version ]
Curves are algebraic K(pi,1): theoretical and practical aspects
Christophe Levrat [Bulletin of the London Mathematical Society, 2024]
 [ arXiv | published version ]
Proofs of non-Supermajority: the missing link for two-phase BFT with responsive view-change and linear complexity
Christophe Levrat, Matthieu Rambaud [Preprint]
 [ eprint | Go code ]
Practical Non-interactive Multi-signatures, and a Multi-to-Aggregate Signatures Compiler
Christophe Levrat, Matthieu Rambaud [Preprint]
 [ eprint ]
Breaking the Consensus Bound: Asynchronous Dynamic Proactive Secret Sharing under Honest Majority
Christophe Levrat, Matthieu Rambaud, Antoine Urban [Preprint]
 [ eprint | Go code ]
Calcul effectif de la cohomologie des faisceaux constructibles sur le site étale d'une courbe
[PhD Thesis]
 [ arXiv ]

Teaching

I have taught various classes in Mathematics and Computer Science at Sorbonne Université, Télécom Paris, ENSTA Paris and Université Paris 8.

2024, 2025: Information Theory - Université Paris 8, Lectures
2024, 2025, 2026: (MA203) Discrete mathematics - ENSTA Paris, Teaching assistant
2024: (INF109) Algorithmics and foundations of Computer Science - Télécom Paris, Programming sessions
2022, 2023: (MDI210) Numerical analysis and optimisation - Télécom Paris, Lectures and programming sessions
2023: (INF105) Formal languages - Télécom Paris, Lectures
2021: (LU2MA263) Linear and bilinear algebra IIb - Sorbonne Université, Teaching assistant
2020, 2021: (LU3MA270) Algebra - Sorbonne Université, Teaching assistant
2019: (LU1MA001) Mathematics for science studies - Sorbonne Université, Teaching assistant

Experiences

Postdoctoral researcher

May 2024 - Present
Inria Saclay, GRACE Team

Postdoctoral researcher

Oct. 2022 - Apr. 2024
Télécom Paris, LTCI

PhD student

2019-2022
Sorbonne Université, IMJ-PRG

Research intern

April-July 2018
Inria Saclay, GRACE Team