ECRYPT II is a NoE in the area of cryptology with a duration of 54 months. Cryptology is the science that studies mathematical techniques in order to provide secrecy, authenticity and related properties for digital information including the secure implementations of these techniques. It is an interdisciplinary research area with a high strategic impact for European industry and for the society as a whole. It is a fundamental enabler for secure, dependable and trusted infrastructures. The ECRYPT II research roadmap is motivated by the changing environment and threat models in which cryptology is deployed, by the gradual erosion of the computational difficulty of the mathematical problems on which cryptology is based, and by the requirements of new applications and cryptographic implementations. Its main objective is to ensure a durable integration of European research in both academia and industry and to maintain and strengthen the European excellence in these areas. In order to reach this goal, 11 leading players propose to integrate their research capabilities within three virtual labs focusing on symmetric key algorithms, public key algorithms and protocols, and hardware and software implementation. They will be joined by more than 20 adjoint members to the network who will closely collaborate with the core partners. ECRYPT II plans to build on an expand the integration activities developed within ECRYPT that include joint workshops, exchange of researchers and students, development of common tools and benchmarks and a website and forum which will be a focal point for the network and the wider cryptographic community. Spreading activities will include a training program, a substantial contribution towards standardization, bodies and an active publication policy. The project team has the critical mass and breadth to address the key questions in these areas.
In a multisecret sharing scheme, several secret values are distributed among a set of n users, and each secret may have a differ-
ent associated access structure. We consider here unconditionally secure schemes with multithreshold access structures. Namely, for every subset P of k users there is a secret key that can only be computed when at
least t of them put together their secret information. Coalitions with at most w users with less than t of them in P cannot obtain any information about the secret associated to P. The main parameters to optimize are
the length of the shares and the amount of random bits that are needed to set up the distribution of shares, both in relation to the length of the secret. In this paper, we provide lower bounds on this parameters.
Moreover, we present an optimal construction for t = 2 and k = 3, and a construction that is valid for all w, t, k and n. The models presented use linear algebraic techniques.
Cramer, R.; Daza, V.; Gracia, I.; Jimenez, J.; Leander, G.; Martí-Farré, J.; Padro, C. IEEE transactions on information theory Vol. 54, num. 6, p. 2644-2657 Data de publicació: 2008-06 Article en revista
Padro, C.; Gracia, I.; Martin, S.; Morillo, M. World Multiconference on Systemics, Cybernetics and Informatics and International Conference on Information Systems, Analysis and Synthesis p. 526-531 Presentació treball a congrés