511 résultats
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L1 a new quasi-linear LLL algorithm
Orateur : Andy Novocin - ENS Lyon
The LLL lattice reduction algorithm of 1982 has proven to be useful in a wide variety of fields. It can be used to approximately solve computationally difficult lattice-based problems, such as the shortest vector problem, in polynomial time. We present a new algorithm for lattice reduction which is the first algorithm to have a complexity bound which is both polynomial and quasi-linear bound in[…] -
Cryptographic Approach to Private Social Clouds
Orateur : Marc Manulis - Technische Universität Darmstadt
Users increasingly rely on the ``social cloud'' for storing and sharing personal information, for establishing new contacts, and for interacting with their friends and colleagues. Even though social media platforms may differ in the target audience, in the nature of collected and disseminated information, and in services offered to the users, there are several building blocks that enable[…] -
Design and Analysis of Opaque Signatures
Orateur : Laila El Aimani - Technicolor
Digital signatures were introduced to guarantee the authenticity and integrity of the underlying messages. However, and in situations where the signed data is commercially or personally sensitive, the universal verification of digital signatures is undesirable, and needs to be limited or controlled. Therefore, mechanisms which share most properties with digital signatures except the universal[…] -
Wild McEliece Incognito
Orateur : Christiane Peters - Technische Universiteit Eindhoven
The McEliece cryptosystem is based on classical Goppa codes over F_2. Generalizations of the McEliece cryptosystem using Goppa codes over larger fields F_q were investigated but not found to offer advantages for small q. We showed that codes over F_31 offer advantages in key size compared to codes over F_2 while maintaining the same security level against all attacks known. However, codes over[…] -
Deterministic equation solving over finite fields
Orateur : Christiaan van de Woestijne - Montanuniversität Leoben
It is a curious fact that most efficient algorithms for solving algebraic equations over finite fields are probabilistic. In this talk, I will give an overview over deterministic techniques that are applicable. The case of constructing rational points on elliptic curves is especially relevant for cryptographic applications. I will give a detailed exposition of my algorithm for this purpose and[…] -
Un algorithme de résolution des équations quadratiques
Orateur : Pierre Castel - Université de Caen
Soit Q une forme quadratique de dimension 5. Le but de cet algorithme est de trouver un vecteur isotrope pour la forme Q. Des algorithmes existent déjà pour résoudre ce type d'équation, cependant la première étape de ces algorithmes consiste à factoriser le déterminant de Q ce qui nuit considérablement à leur efficacité. Dans cet exposé, je proposerai un nouvel algorithme ne factorisant pas[…]