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Accueil du site > Séminaires et journées internes > Séminaires de CRYPTO > Séminaires CRYPTO 2017-2018

Séminaires CRYPTO 2017-2018

Agenda

séminaire

    • Mardi 10 avril 14:00-15:00 - Ferdinand Sibleyras - Inria Paris

      The Missing Difference Problem, and its Applications to Counter Mode Encryption

      Résumé : The widely deployed counter mode (CTR) is known for its efficiency and simplicity as it comes with a security proof that guarantees no attack up to the birthday bound and a matching distinguishing attack. However, unlike in CBC mode, a ciphertext collision in CTR mode hardly reveals anything to the attacker. Therefore we define an algorithmic problem, the missing difference problem, and show how its resolution leads to a message recovery attack with complexity close to the birthday bound. As a further result efficiently solving this problem also allows to describe an universal forgery attack against polynomial MACs such as GMAC and Poly1305 in complexity Õ(2^(2n/3)).
      This is a joint work with Gaëtan Leurent.

      Lieu : Bât. Descartes, Salle 301


    • Mardi 17 avril 14:00-15:00 - Albrecht Petzoldt - UVSQ

      Improved Cryptanalysis of HFEv- via Projection

      Résumé : The HFEv- signature scheme is one of the most studied multivariate schemes and one of the major candidates for the upcoming standardization of post-quantum digital signature schemes. In this paper, we propose three new attack strategies against HFEv-, each of them using the idea of projection. Especially our third attack is very effective and is, for some parameter sets, the most efficient known attack against HFEv-. Furthermore, our attack requires much less memory than direct and rank attacks. By our work, we therefore give new insights in the security of the HFEv- signature scheme and restrictions for the parameter choice of a possible future standardized HFEv- instance.


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Séminaire dédié à la cryptographie et à la sécurité informatique. Ce séminaire, ouvert à tous, a généralement lieu le vendredi matin de 11h à 12h en salle 301 du bâtiment Descartes.

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Mots-clés

Cryptographie