Guilhem Castagnos

Publications

An Improved Threshold Homomorphic Cryptosystem Based on Class Groups, with Lennart Braun, Ivan Damgård, Fabien Laguillaumie, Kelsey Melissaris, Claudio Orlandi and Ida Tucker, SCN'2024, [DOI] [EPRINT]

I want to ride my BICYCL: BICYCL Implements CryptographY in CLass groups, with Cyril Bouvier, Laurent Imbert and Fabien Laguillaumie, Journal of Cryptology, Topical Collection on Computing on Encrypted Data, 2023 [DOI] [PDF]

Pattern Matching in Encrypted Stream from Inner Product Encryption, with Élie Bouscatié and Olivier Sanders, PKC'2023, [DOI] [PDF]

Bandwidth-efficient threshold EC-DSA revisited: Online/Offline Extensions, Identifiable Aborts, Proactivity and Adaptive Security, with Dario Catalano, Fabien Laguillaumie, Federico Savasta and Ida Tucker, Theoretical Computer Science, 2023 [DOI] [PDF]

Threshold Linearly Homomorphic Encryption on Z/2^kZ, with Fabien Laguillaumie and Ida Tucker, ASIACRYPT'2022 [PDF]

A Tighter Proof for CCA Secure Inner Product Functional Encryption: Genericity Meets Efficiency with Fabien Laguillaumie and Ida Tucker, Theoretical Computer Science, 2022 [DOI] [PDF]

Public Key Encryption with Flexible Pattern Matching, with Élie Bouscatié and Olivier Sanders, ASIACRYPT'2021 [DOI] [PDF]

Efficient CCA Timed Commitments in Class Groups, with Sri Aravinda Krishnan Thyagarajan, Fabien Laguillaumie and Giulio Malavolta, ACM CCS 2021 [DOI] [PDF]

Bandwidth-efficient threshold ECDSA, with Dario Catalano, Fabien Laguillaumie, Federico Savasta and Ida Tucker, PKC'2020 [DOI] [PDF]

Two-Party ECDSA from Hash Proof Systems and Efficient Instantiations, with Dario Catalano, Fabien Laguillaumie, Federico Savasta and Ida Tucker, CRYPTO'2019 [DOI] [PDF]

Practical Fully Secure Unrestricted Inner Product Functional Encryption modulo p, with Fabien Laguillaumie and Ida Tucker, ASIACRYPT'2018 [DOI] [PDF]

Encryption Switching Protocols Revisited: Switching modulo p, with Laurent Imbert and Fabien Laguillaumie, CRYPTO'2017 [DOI] [PDF]

Linearly Homomorphic Encryption from DDH, with Fabien Laguillaumie, CT-RSA'2015 [DOI] [PDF]

High-Order Masking by Using Coding Theory and its Application to AES, with Soline Renner and Gilles Zémor, IMACC'2013 [DOI] [PDF]

Homomorphic Encryption for Multiplications and Pairing Evaluation, with Fabien Laguillaumie, SCN'2012 [DOI] [PDF]

Factoring pq² with Quadratic Forms: Nice Cryptanalyses, with Antoine Joux, Fabien Laguillaumie and Phong Q. Nguyen, ASIACRYPT'2009 [DOI] [PDF]

Fault Analysis of Grain-128, with Alexandre Berzati, Cécile Canovas, Blandine Debraize, Louis Goubin, Aline Gouget, Pascal Paillier and Stéphanie Salgado, HOST 2009 [DOI] [PDF]

On the Security of Cryptosystems with Quadratic Decryption: The Nicest Cryptanalysis, with Fabien Laguillaumie, EUROCRYPT'2009 [DOI] [PDF]

Two Generic Constructions of Probabilistic Cryptosystems and their Applications, SCN'2008 [DOI] [PDF]

Lattice-based homomorphic encryption of vector spaces, with Carlos Aguilar Melchor and Philippe Gaborit ISIT'2008 [DOI] [PDF]

Towards a DL-based Additively Homomorphic Encryption Scheme, with Benoît Chevallier-Mames, ISC'2007 [DOI] [PDF]

Trapdoor Permutation Polynomials of Z/nZ and Public Key Cryptosystems, with Damien Vergnaud ISC'2007 [DOI] [PDF]

An efficient probabilistic public-key cryptosystem over quadratic fields quotients, Finite Fields and Their Applications, 2007 [DOI] [PDF]

HDR [↑]

I have defended my habilitation à diriger des recherches the 8th of november 2019. The Thesis [pdf].

Title:: Cryptography based on quadratic fields: cryptanalyses, primitives and protocols
Reviewers:: David Pointcheval, Directeur de recherche à l'É.N.S. Paris; Renate Scheidler, Professeure à l'université de Calgary; Damien Stehlé, Professeur à l'É.N.S. de Lyon
Jury:: Pierrick Gaudry, Directeur de recherche au Loria; Louis Goubin, Professeur à l'université de Versailles-Saint-Quentin; David Pointcheval, Directeur de recherche à l'É.N.S. Paris; Damien Stehlé, Professeur à l'É.N.S. de Lyon; Damien Vergnaud, Professeur à Sorbonne Université; Gilles Zémor, Professeur à l'université de Bordeaux

Ph.D. Thesis [↑]

I have started my Ph.D. Thesis at the University of Limoges in October 2003. I have defended this Thesis the 3rd of October 2006. The Thesis: [pdf].

Title:

Some asymmetric cryptography probabilistic schemes

Supervisors:

François Arnault, maître de conférences à l'université de Limoges

Thierry Berger, professeur à l'université de Limoges

Jury :

Président :: Moulay Barkatou, professeur à l'université de Limoges
Rapporteurs :: Jean-Marc Couveignes, professeur à l'université Toulouse II; François Morain, professeur associé à l'école polytechnique, H.D.R.
Examinateurs :: François Arnault, maître de conférences à l'université de Limoges; Thierry Berger, professeur à l'université de Limoges; David Pointcheval, chargé de recherche à l'É.N.S., H.D.R.