Augustin Bariant

Symmetric cryptography expert at ANSSI

WHO AM I

Former student at École Polytechnique, I completed a double degree with KTH Royal Institute of Technology in Stockholm in 2021. In march 2021, I started a Ph.D in symmetric cryptography in the team COSMIQ of Inria de Paris, under the supervision of Gaëtan Leurent. There, I mainly worked on boomerang attacks against AES-based ciphers and algebraic attacks against arithmetization-oriented primitives. I also codesigned LeMac, which is the fastest MAC in the literature on modern processors to this day. I defended my PhD on the 27/06/2024.
I am currently working as an expert in the cryptography laboratory of ANSSI, and am still performing research. I am mainly interested in other types of attacks on SPN ciphers, e.g. impossible differential or square attacks, and I am still actively involved in the algebraic cryptanalysis of arithmetization-oriented primitives. I also enjoy designing and breaking crypto challenges in CTF competitions. You can find my resumé in french here.

PhD

• Title: Analysis of AES-based and arithmetization-oriented symmetric cryptography primitives.
• Defense: On the 27/06/2024 at École Normale Supérieure Paris.
• Manuscript.
• Slides.

Teaching

2017-2018

• Tutor in mathematics for first-year students (MPSI) in the preparatory school Lycée Louis Le Grand.

2021-2022

• Teaching assistant (TP) for the first year class LU1IN011 at Sorbonne Université (SU): Introduction to Programming in Python.
• Teaching assistant (TP) for the second year class LU2IN019 at SU: Functional Programming.
• Teaching assistant (TD+TP) for the third year class LU3IN024 at SU: Introduction to Cryptology.
• Teaching assistant (TD+TP) for the third year class LU2IN017 at SU: Web Technologies.

2022-2023

• Teaching assistant (TP) for the first year class LU1IN011 at SU: Introduction to Programming in Python.
• Teaching assistant (TP) for the second year class LU2IN019 at SU: Functional Programming.

Talks

• Fast Software Encryption (FSE), 2020: Cryptanalysis of Forkciphers (first part).
• Journées C2, 2022: Generating Bitslice Implementations of Arbitrary S-Boxes.
• Junior Seminar, 2022: Algebraic Attacks against Some Arithmetization-Oriented Hash Functions.
• Séminaire de Versailles, 2022: Algebraic Attacks against Some Arithmetization-Oriented Symmetric Cryptographic Algorithms.
• Journées C2, 2023: Truncated Boomerang Attacks and Application to AES-based Ciphers.

Publications

1.	A. Bariant, N. David, G. Leurent, Cryptanalysis of Forkciphers, IACR Transactions on Symmetric Cryptology (ToSC) 2020, volume 1.
2.	A. Bariant, C. Bouvier, G. Leurent, L. Perrin, Algebraic Attacks against Some Arithmetization-Oriented Primitives, IACR Transactions on Symmetric Cryptology (ToSC) 2022, volume 3.
3.	A. Bariant, G. Leurent, Truncated Boomerang Attacks and Application to AES-based Ciphers, EUROCRYPT 2023.
4.	A. Bariant, A. Boeuf, A. Lemoine, I. Manterola Ayala, M. Øygarden, L. Perrin, H. Raddum, The Algebraic Freelunch: Efficient Gröbner Basis Attacks Against Arithmetization-Oriented Primitives, CRYPTO 2024.
5.	A. Bariant, J. Baudrin, G. Leurent, C. Pernot, L. Perrin, T. Peyrin, Fast AES-Based Universal Hash Functions and MACs: Featuring LeMac and PetitMac, IACR Transactions on Symmetric Cryptology (ToSC) 2024, volume 2.
6.	A. Bariant, A Univariate Attack on a Full Ciminion Instance, Selected Areas in Cryptography (SAC) 2024.
7.	A. Bariant, O. Dunkelman, N. Keller, G. Leurent, V. Mollimard, Improved Boomerang Attacks on 6-Round AES, EPRINT 2024.