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684 results

    • Seminar

    • Cryptography

    ECDSA White-Box Implementations, Feedback on CHES 2021 WhibOx Contest

    • September 29, 2023

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

    Speaker : Agathe Houzelot - Idemia

    Cryptographic algorithms are primarily designed to be secure in the black-box model, where an attacker can only observe their input/output behavior. However in practice, algorithms are rarely executed in a completely isolated environment and additional information is often leaked. In the context of mobile applications or connected objects, devices often lack secure storage to protect secret keys,[…]
    • Seminar

    • Cryptography

    Password-Authenticated Key Exchange (PAKE) from Isogenies

    • December 08, 2023

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

    Speaker : Sabrina Kunzweiler - Université Bordeaux

    The passwords that we use in our everyday life are often chosen to be easily memorable which makes them vulnerable to attacks. This problem is addressed by password-authenticated key exchange (PAKE). The general idea is to enable two parties who share the same (potentially weak) password to establish a strong session key. Most PAKE protocols used today are based on Diffie-Hellman key exchange in[…]
    • Seminar

    • Cryptography

    Updatable Public Key Encryption with Lattices

    • February 23, 2024

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

    Speaker : Calvin Abou-Haidar - ENS Lyon

    Updatable public key encryption has recently been introduced as a so- lution to achieve forward-security in the context of secure group messaging without hurting efficiency, but so far, no efficient lattice-based instantia- tion of this primitive is known. In this work, we construct the first LWE-based UPKE scheme with polynomial modulus-to-noise rate, which is CPA-secure in the standard model. At[…]
    • Seminar

    • Cryptography

    Correction of dual lattice attacks

    • April 19, 2024

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

    Speaker : Kevin Carrier - CY Cergy

    The security of cryptographic systems such as Kyber and Dilithium (currently undergoing standardization by NIST) fundamentally hinges on the Learning With Errors (LWE) problem. However, the state of the art for attacking this problem is not yet entirely clear. Specifically, the validity of dual attacks on LWE is currently under scrutiny due to their analyses relying on heuristics that have proven[…]
    • Seminar

    • Cryptography

    Generic Attack on Duplex-Bases AEAD Modes using Random Function Statistics

    • September 22, 2023

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

    Speaker : Rachelle Heim Boissier - Inria

    Duplex-based authenticated encryption modes with a sufficiently large key length are proven to be secure up to the birthday bound 2^(c/2), where c is the capacity. However this bound is not known to be tight and the complexity of the best known generic attack, which is based on multicollisions, is much larger: it reaches 2^c/α where α represents a small security loss factor. There is thus an[…]
    • Seminar

    • Cryptography

    Finding short integer solutions when the modulus is small

    • November 24, 2023

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

    Speaker : Eamonn Postlethwaite - King's College London

    We present cryptanalysis of the inhomogenous short integer solution (ISIS) problem for anomalously small moduli by exploiting the geometry of BKZ reduced bases of q-ary lattices. We apply this cryptanalysis to examples from the literature where taking such small moduli has been suggested. A recent work [Espitau–Tibouchi–Wallet–Yu, CRYPTO 2022] suggests small versions of the lattice signature[…]