Description
Lyubashevsky’s signatures are based on the Fiat-Shamir with aborts paradigm, whose central ingredient is the use of rejection sampling to transform (secret-key-dependent) signature samples into samples from a secret-key-independent distribution. The choice of these two underly- ing distributions is part of the rejection sampling strategy, and various instantiations have been considered up to this day. In this work, we inves- tigate which strategy leads to the most compact signatures, given signing runtime requirements. Our main contributions are as follows:<br/> (i) We prove lower bounds for compactness of signatures given signing runtime requirements, and (ii) show that these lower bounds are reached considering a new and elementary choice of distributions, namely con- tinuous uniform distributions over hyperballs. (iii) We also prove that, for any fixed pair of distributions, classic rejection sampling is the best strategy for minimizing the number of aborts, as well as (iv) propose a novel strategy that allows to fix (any) bound on the number of aborts while still guaranteeing correctness and security.<br/> lien: https://univ-rennes1-fr.zoom.us/j/97066341266?pwd=RUthOFV5cm1uT0ZCQVh6QUcrb1drQT09
Prochains exposés
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Algorithms for post-quantum commutative group actions
Orateur : Marc Houben - Inria Bordeaux
At the historical foundation of isogeny-based cryptography lies a scheme known as CRS; a key exchange protocol based on class group actions on elliptic curves. Along with more efficient variants, such as CSIDH, this framework has emerged as a powerful building block for the construction of advanced post-quantum cryptographic primitives. Unfortunately, all protocols in this line of work are[…] -
Endomorphisms via Splittings
Orateur : Min-Yi Shen - No Affiliation
One of the fundamental hardness assumptions underlying isogeny-based cryptography is the problem of finding a non-trivial endomorphism of a given supersingular elliptic curve. In this talk, we show that the problem is related to the problem of finding a splitting of a principally polarised superspecial abelian surface. In particular, we provide formal security reductions and a proof-of-concept[…]-
Cryptography
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