Table of contents

  • This session has been presented January 24, 2025 (13:45 - 14:45).

Description

  • Speaker

    Maxime Romeas - ANSSI

Updatable Encryption is a variant of symmetric encryption that allows to rotate the encryption key in the outsourced storage setting while minimizing the bandwith used. Indeed, any third party can update ciphertexts to the new key using a token provided by the key holder. UE schemes aim at providing strong confidentiality guarantees against adversaries that can corrupt keys and tokens. 

In this talk, I will give an overview of Updatable Encryption, show how to build post-quantum Updatable Encryption schemes using cryptographic group actions and give an instantiation based on isogenies. This is the first post-quantum Updatable Encryption construction not based on lattices and that allows an unlimited number of updates.

This is joint-work with Antonin Leroux (DGA-MI & IRMAR).

Reference: A. Leroux and M. Roméas. Updatable Encryption from Group Actions. PQCrypto 2024.

 

Practical infos

Next sessions

  • Predicting Module-Lattice Reduction

    • December 19, 2025 (13:45 - 14:45)

    • Batiment 22-23 salle 16 (en face de l'amphi Lebesgue)

    Speaker : Paola de Perthuis - CWI

    Is module-lattice reduction better than unstructured lattice reduction? This question was highlighted as `Q8' in the Kyber NIST standardization submission (Avanzi et al., 2021), as potentially affecting the concrete security of Kyber and other module-lattice-based schemes. Foundational works on module-lattice reduction (Lee, Pellet-Mary, Stehlé, and Wallet, ASIACRYPT 2019; Mukherjee and Stephens[…]

    • Cryptography

  • Séminaire C2 à INRIA Paris

    • January 16, 2026 (10:00 - 17:00)

    • INRIA Paris

    Emmanuel Thomé et Pierrick Gaudry Rachelle Heim Boissier Épiphane Nouetowa Dung Bui Plus d'infos sur https://seminaire-c2.inria.fr/ 

  • Attacking the Supersingular Isogeny Problem: From the Delfs–Galbraith algorithm to oriented graphs

    • January 23, 2026 (13:45 - 14:45)

    • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

    Speaker : Arthur Herlédan Le Merdy - COSIC, KU Leuven

    The threat of quantum computers motivates the introduction of new hard problems for cryptography.One promising candidate is the Isogeny problem: given two elliptic curves, compute a “nice’’ map between them, called an isogeny.In this talk, we study classical attacks on this problem, specialised to supersingular elliptic curves, on which the security of current isogeny-based cryptography relies. In[…]

    • Cryptography

Show previous sessions
Page top