Description
In 1998, Blaze, Bleumer, and Strauss proposed a cryptographic primitive called proxy re-encryption, in which a proxy transforms - without seeing the corresponding plaintext - a ciphertext computed under Alice's public key into one that can be opened using Bob's secret key. Recently, an appropriate definition of chosen-ciphertext security and a construction fitting this model were put forth by Canetti and Hohenberger. Their system is bidirectional: the information released to divert ciphertexts from Alice to Bob can also be used to translate ciphertexts in the opposite direction. In this presentation, we will present the first construction of unidirectional proxy re-encryption scheme with chosen-ciphertext security in the standard model (i.e. without relying on the random oracle idealization), which solves a problem left open at CCS'07. Our construction is efficient and requires a reasonable complexity assumption in bilinear map groups. Like the Canetti-Hohenberger scheme, it ensures security according to a relaxed definition of chosen-ciphertext introduced by Canetti, Krawczyk and Nielsen. (joint work with Benoît Libert)
Prochains exposés
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Random lattices that are modules over the ring of integers
Orateur : Nihar Gargava - Institut de Mathématiques d'Orsay
We investigate the average number of lattice points within a ball where the lattice is chosen at random from the set of unit determinant ideal or modules lattices of some cyclotomic number field. The goal is to consider the space of such lattice as a probabilistic space and then study the distribution of lattice point counts. This is inspired by the connections of this problem to lattice-based[…]-
Cryptography
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Schéma de signature à clé publique : Frobénius-UOV
Orateur : Gilles Macario-Rat - Orange
L'exposé présente un schéma de signature à clé publique post-quantique inspiré du schéma UOV et introduisant un nouvel outil : les formes de Frobénius. L'accent est mis sur le rôle et les propriétés des formes de Frobénius dans ce nouveau schéma : la simplicité de description, la facilité de mise en oeuvre et le gain inédit sur les tailles de signature et de clé qui bat RSA-2048 au niveau de[…] -
Yoyo tricks with a BEANIE
Orateur : Xavier Bonnetain - Inria
TBD-
Cryptography
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Symmetrical primitive
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