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Séminaire
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Cryptographie
Improved Veron Identification and Signature Schemes in the Rank Metric
Orateur : Florian Caullery - Darkmatter
Abstract—It is notably challenging to design an efficient and secure signature scheme based on error-correcting codes. An approach to build such signature schemes is to derive it from an identification protocol through the Fiat-Shamir transform.<br/> All such protocols based on codes must be run several rounds, since each run of the protocol allows a cheating probability of either 2/3 or 1/2. The[…] -
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Séminaire
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Cryptographie
Towards Non-Interactive Zero-Knowledge from CDH and LWE
Orateur : Geoffroy Couteau - Karlsruher Institut für Technologie (KIT)
We provide a generic construction of non-interactive zero-knowledge (NIZK) schemes. Our construction is a refinement of Dwork and Naor’s (FOCS 2000) implementation of the hidden bits model using verifiable pseudorandom generators (VPRGs). Our refinement simplifies their construction and relaxes the necessary assumptions considerably. As a result of this conceptual improvement, we obtain[…] -
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Séminaire
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Cryptographie
Lossy trapdoor primitives, zero-knowledge proofs and applications
Orateur : Chen Qian - soutenance de thèse salle Métivier à l'IRISA, 14h
In this thesis, we study two differentprimitives. Lossy trapdoor functions and zero-knwoledge proof systems.The lossy trapdoor functions (LTFs) arefunction families in which injective functionsand lossy ones are computationally indistin-guishable. Since their introduction, they havebeen found useful in constructing various cryp-tographic primitives. We give in this thesisefficient constructions of[…] -
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Séminaire
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Cryptographie
Improved Cryptanalysis of Rank Metric Schemes Based on Gabidulin Codes.
Orateur : Hervé Talé Kalachi - Université de Rouen et Université de Yaoundé, Cameroun
In this presentation, we prove that any variant of the GPT cryptosystem which uses a right column scrambler over the extension field as advocated by the works of Gabidulin et al. with the goal to resist to Overbeck’s structural attack are actually still vulnerable to that attack. We show that by applying the Frobenius operator appropriately on the public key, it is possible to build a Gabidulin[…] -
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Séminaire
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Cryptographie
Investigating LWE without Modular Reduction
Orateur : Jonathan Bootle - UCL
The LWE problem is ubiquitous in lattice cryptography. In order to try and design more efficient cryptosystems, an increasing number of LWE variants are being considered. In this talk, we consider a variant of LWE over the integers i.e. without modular reduction. We explain why the problem is easy to solve with a large number of samples, and show how this leads to a side-channel attack on the[…] -
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Séminaire
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Cryptographie
A Modular Security Analysis of EAP and IEEE 802.11
Orateur : Haakon Jacobsen - TBD
The Extensible Authentication Protocol (EAP) is a widely used three-party authentication framework that allows a client to connect to a wireless access point it does not share a secret with, using a mutually trusted server. EAP is often found in enterprise networks or large organizations to provide central key-management and user authentication; one prime example being the eduroam network.<br/> In[…] -