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Deim Seminar


Optimization of Secret Sharing Schemes (II): Multipartite Secret Sharing Schemes


Oriol Farrs Ventura

Professor/a organitzador/a



Universitat Rovira i Virgili


16-11-2010 12:00


A secret sharing scheme is a cryptographic method to protect a piece of information or data by dividing it into pieces, which are called shares, in such a way that it can only be recovered from certain subsets of shares. Secret sharing schemes are a very important primitive in cryptography, mainly due to the fact that secret sharing is an essential building block in multiparty computation protocols. Multiparty computation is a very general notion that covers many different kinds of protocols, as electronic elections, electronic biddings, data base access and data base computations, and joint signatures. Considering that each share is held by a participant, the access structure of the scheme is defined as the family of coalitions of participants that can recover the secret. Ideal secret sharing schemes are those in which the size of the shares is the same as the size of the secret, which is the best possible situation. However, not all access structures admit ideal schemes, and the general bounds for the size of the shares is exponential on the number of participants. The optimization of secret sharing schemes is one of the main open problems in secret sharing. The aim of this talk is to present new results obtained in this area. In particular, the results on multipartite secret sharing schemes and the combinatorial and algebraic techniques that have been used.


Laboratori 231