Thomas ⠵ Espitau

head of research @pqshield

Image

.about & misc

I pursued my Ph.D. in algorithmic number theory and cryptography at Sorbonne University in Paris, advised by prof. Antoine Joux and prof. Pierre-Alain Fouque. I then joined NTT laboratories in Tokyo, Japan. I joined the PQShield research team in 2023.

I am an enthusiastic surfer and freeride skier. Please drop me a line if you need some infos/tips/guiding on the best hidden gems of Japanese mountains and breaks.my Erdős number is 3 (by Joux>>Odlyzko>>Erdős)

.: news

  • I will be presenting Efficient Threshold ML-DSA with Sofia Celi at RWC 2026 !

  • I am in Japan for January/February; drop me a line if you want to meet there !

  • our former student Guilhem Niot received the Kudelski prize🏆 for his master work on the Squirrels signature , congratulations !

.: (some) recent publications

.: (some) selected talks

.: research interests

My ongoing explorations are about the algorithmic classification of low dimensional hermitian forms over number fields. Drop me a line if you want to have a chat !

  • geometry of numbers and lattices (theta functions, discrete geometry, Arakelov theory on F1)

  • (algorithmic) number theory (reduction of vector bundles over arithmetic curves curves, effective Arakelov)

  • lattice-based cryptography (cryptanalysis, threshold cryptography, secure implementation)

.: projects

  • NIST threshold signature mithril🏔️

  • NIST proposal signature raccoon 🦝

  • NIST proposal signature squirrels 🐿️

.: students

  • Mathilde Kermorgant | Master student 2026

  • Sara Sahraee | Master student, 2024

  • Георгій Пляцок (Georgii Platsiok) | Ph.D student, 2024

  • Guilhem Niot | Master student, 2023

Have a look at the careers page of PQShield. We are looking for excellent permanent as well as PhD/post-doctoral researchers to work within our research team. Funding is available. I am also looking for very talented interns (master or PhD students). Please send your resume and background!

© 2024 thomas espitau

Image

.about

I pursued my Ph.D. in algorithmic number theory and cryptography at Sorbonne University in Paris, advised by prof. Antoine Joux and prof. Pierre-Alain Fouque. I then joined NTT laboratories in Tokyo, Japan. I joined the PQShield research team in 2023.

I am an enthusiastic surfer and freeride skier. Please drop me a line if you need some infos/tips/guiding on the best hidden gems of Japanese mountains and breaks.my Erdős number is 3 (by Joux>>Odlyzko>>Erdős)

.: phd thesis

Algorithmic aspects of algebraic lattices. (Aspects algorithmiques des réseaux algébriques) 2020, Sorbonne University.
Prepared under the supervision of Prof. Pierre Alain Fouque and Prof. Antoine Joux

.: publication list, by year

2026

2025

2024

2023

  • 29.On Gaussian Sampling, Smoothing Parameter and Application to Signatures (with A .Wallet, Y. Yu) | Asiacrypt 2023 Best paper Award

  • 28.Antrag: Annular NTRU Trapdoor Generation: Making Mitaka as Secure as Falcon (with T. Nguyen, C. Sun, M. Tibouchi, A. Wallet) Asiacrypt 2023

  • 27.Finding short integer solutions when the modulus is small (with L. Ducas, E. Postlethwaite) Crypto 2023

  • 26.Square Unstructured Integer Euclidean Lattice Signature (with G. Niot, C. Sun, M. Tibouchi) Submission to the NIST’s post-quantum cryptography standardization process 2023

  • 25.Recursive lattice reduction--A framework for finding short lattice vectors (with D. Aggarwal, S. Peters, N. Stephens-Davidowitz)

2022

  • 24.Shorter hash-and-sign lattice-based signatures (with M. Tibouchi, A. Wallet, Y. Yu) Crypto 2022

  • 23.Mitaka: a simpler, parallelizable, maskable variant of falcon (with P. Fouque, F. Gérard, M. Rossi, A. Takahashi, M. Tibouchi, A. Wallet, Y. Yu) Eurocrypt 2022

  • 22.Guessing bits: improved lattice attacks on (EC)DSA with nonce leakage (with C. Sun, M. Tibouchi, M. Abe) IACR Transactions on Symmetric Cryptology 2022

2021

  • 21.Towards Faster Polynomial-Time Lattice Reduction (with P Kirchner, P-A Fouque) Crypto 2021

2020

  • 20.Fast Reduction of Algebraic Lattices over Cyclotomic Fieldsn (with P Kirchner, P-A Fouque) Crypto 2020

  • 19.Certified lattice reduction (with A. Joux) Adv. Math. Commun

  • 18.On a Dual/Hybrid Approach to Small Secret LWE - A Dual/Enumeration Technique for Learning with Errors and Application to Security Estimates of FHE Schemes (with N. Karchenko, A. Joux) Indocrypt 2020

2019

  • 17.Relational ⋆⋆ tar-Liftings for Differential Privacy(with G. Barthe, B. Grégoire, T. Sato, P-Y. Strub) [Log. Methods Comput. Sci.]

  • 16.GALACTICS: Gaussian Sampling for Lattice-Based Constant-Time Implementation of Cryptographic Signatures, Revisited(with G. Barthe, S. Belaïd, P. Fouque, B. Grégoire, M. Rossi, M. Tibouchi) Eurocrpyt 2019

2018

  • 15.Proving expected sensitivity of probabilistic programs. (with G. Barthe, B. Grégoire, J. Hsu, P-Y. Strub ) POPL 2018

  • 14.Loop-Abort Faults on Lattice-Based Signature Schemes and Key Exchange Protocols (with P-A. Fouque, B. Gerard, M. Tibouchi) IEEE Trans. Computers

  • 13.LWE Without Modular Reduction and Improved Side-Channel Attacks Against BLISS(with J. Bootle, C. Delaplace, P. Fouque, M. Tibouchi) Asiacrypt 2018

  • 12.An Assertion-Based Program Logic for Probabilistic Programs(with G. Barthe, M. Gaboardi, B. Grégoire, J Hsu, P-Y Strub:) ESOP 2018

  • 11.Masking the GLP Lattice-Based Signature Scheme at Any Order(with G. Barthe, S. Belaïd, P. Fouque, B. Grégoire, M. Rossi, M. Tibouchi) Eurocrypt 2018

2017

  • 10.Side-channel attacks on BLISS lattice-based signatures: Exploiting branch tracing against strongswan and electromagnetic emanations in microcontrollers (with P. Fouque, B. Gérard, M. Tibouchi) CCS 2017

  • 9.Liftings for differential privacy (with G. Barthe, J. Hsu, T. Sato, P. Strub) ICALP 2017

  • 8.Computing Generator in Cyclotomic Integer Rings - A Subfield Algorithm for the Principal Ideal Problem in LΔ(½) and Application to the Cryptanalysis of a FHE Scheme (with JF Biasse, PA Fouque, A Gélin, P Kirchner) hard merge Eurocrypt 2017

  • 7.Proving expected sensitivity of probabilistic programs (with G. Barthe, B. Grégoire, J. Hsu, P. Strub) POPL 2017

2016

  • 5.Loop-abort faults on lattice-based fiat-shamir and hash-and-sign signatures (with P. Fouque, B. Gérard, M. Tibouchi) SAC 2016

  • 4.Synthesizing probabilistic invariants via Doob’s decomposition (with G. Barthe, L. Ferrer Fioriti, J. Hsu) CAV 2016

  • 3.Formal Certification of Randomized Algorithms (with G. Barthe, M. Gaboardi, B. Grégoire, J. Hsu, P. Strub) Preprint 2016

2015

  • 2.Relational reasoning via probabilistic coupling (with G. Barthe, B. Grégoire, J. Hsu, L. Stefanesco, P. Strub) LPAR 2015

  • 1.Higher-Order Differential Meet-in-The-Middle Preimage Attacks on SHA-1 and BLAKE (with P-A. Fouque, P. Karpman) Crypto 2015

.: unpublished manuscripts

  • -1.Quantum binary quadratic form reduction (with N. David, A. Hosoyamada) 2022

  • -2.Algebraic and Euclidean Lattices: Optimal Lattice Reduction and Beyond (with P-A. Fouque and P. Kirchner) 2019

  • -3.Random integer lattices, theory and practice (with Y. Aono, P. Nguyen) 2018

  • -4.Proving uniformity and independence by self-composition and coupling (with G. Barthe, B. Grégoire, J. Hsu, P. Strub) 2017

© 2024 thomas espitau

Nagano, Japan, 2025

Image
Image
Image
Image

Ripley Creek, British Columbia, march 2024

Image

Niseko, Hokkaido, jan 2022

Image

Hakuba valley, Japan, feb 2023

Image

Anglet, La Barre june 2024

Image
Image

© 2024 thomas espitau