Efficient Attribute-based Cryptography


Séminaire Modèles et Algorithmes Déterministes: CASYS

8/03/2012 - 15:30 Mr Fabien Laguillaumie (Université Caen Basse-Normandie) Salle 1 - Tour IRMA

Public key cryptography aims at providing efficient, versatile, and secure solutions to protect complex systems such as electronic voting, anonymous access control, secure routing,... The foundation of public key cryptography is the existence of hard algorithmic problems, on which the security of these protocols relies. Designing a secure cryptosystem needs a precise identification and analysis of the underlying algorithmic problem, an optimised arithmetic, and a proof of its security according to a model of adversary.

In this talk, I will tackle the design and security analysis of functional cryptosystems, which provide a natural way to protect data in defining a security policy to authorise several users to access (part of) this data. The concept of functional encryption naturally captures those of (anonymous) identity-based encryption and attribute based encryption. As an illustration, I will present efficient attribute based encryption and signature schemes for which the size of the ciphertexts or signatures does not depend on the number of attributes of a user.

This is a joint work with Javier Herranz (UPC, Catalonia), Benoît Libert (UCL, Belgique) and Carla Ràfols (Ruhr-University Bochum, Germany).