Patent ID: 7818570
Filing Date: 2010-10-19
Classification: H04L

Abstract:
1. A computer-implemented method for generating data representing an exclusive set system over a set U of entities such that each element of the exclusive set system is associated with cryptographic data, the method comprising: obtaining, by a computer system comprising circuitry, one or more coordinate systems for the set U, wherein each coordinate system associates each entity in U with a plurality of coordinates; determining, by the computer system, functions ƒ(u) each of which is defined on the set U, each function being a polynomial in one or more of the coordinates of u in at least one of the coordinate systems; determining by the computer system, for each said function ƒ, a corresponding subset S wherein at least one subset S wherein said one or more coordinate systems comprise a first coordinate system which comprises s coordinates where s is a predefined integer greater than one, each coordinate having values in a finite field having fewer elements than the number of entities in the set U; wherein for the first coordinate system, for at least one pair (i,j) of the s coordinates in the first coordinate system, for at least one subset R of U, the following property (A) holds: wherein the method further comprises outputting said first cryptographic data for use by devices as the first input in said cryptographic operation, wherein the devices are for obtaining second cryptographic data for use as the second input in the cryptographic operation to prove the validity property and/or provide the entitlement for each entity of one or more of the subsets S