Description
The Naccache-Stern (NS) knapsack cryptosystem is a little-known public-key encryption scheme, despite (or because of) its original design. In this scheme, the ciphertext is obtained by multiplying the public-keys indexed by the message bits modulo a prime p. The cleartext is then recovered by factoring the ciphertext raised to a secret power modulo p.<br/> NS encryption requires a multiplication per two plaintext bits on the average, while decryption is roughly as costly as an RSA decryption. However, NS features a bandwidth sublinear in log(p), namely log(p)/log(log(p)).<br/> This presentation presents new NS variants allowing to reach bandwidths linear in log(p). The price to pay for reaching a linear bandwidth is a public-key of size log3(p)/log(log(p)). Beyond their mathematical interest, these modifications can possibly make the NS knapsack cryptosystem more practical and attractive. The presentation will be held in French, and will be self-included as much as possible.<br/> This is a joint work with David Naccache (U. Paris II, ENS) and Jacques Stern (ENS) .
Prochains exposés
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Polytopes in the Fiat-Shamir with Aborts Paradigm
Orateur : Hugo Beguinet - ENS Paris / Thales
The Fiat-Shamir with Aborts paradigm (FSwA) uses rejection sampling to remove a secret’s dependency on a given source distribution. Recent results revealed that unlike the uniform distribution in the hypercube, both the continuous Gaussian and the uniform distribution within the hypersphere minimise the rejection rate and the size of the proof of knowledge. However, in practice both these[…]-
Cryptographie
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Primitive asymétrique
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Mode et protocole
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Post-quantum Group-based Cryptography
Orateur : Delaram Kahrobaei - The City University of New York