General information dispersal algorithms

Abstract

We analyse the problem of distributing pieces of a file f among a set of users in such a way that some predefined subsets of users can, pooling together their pieces, reconstruct the entire file f. We call access structure the set of all qualified subsets and we show how to extend the notion of information dispersal algorithms proposed by Rabin (1989, 1990) to general access structures. We give bounds on the amount of information each participant must have. Then, we apply this results to construct optimal or near to optimal schemes for general access structures. Finally, we consider an application of our results to cryptography.