Threshold cryptography scheme for conditional access systems

摘要

A method and apparatus for managing access to a signal representative of an event of a service provider, including receiving said signal in a smart card, said signal being scrambled using a scrambling key, receiving, in said smart card, data representative of a first share; constructing said scrambling key using said first share and at least one additional share, said additional share being stored in said smart card; and descrambling said signal using said constructed scrambling key to provide a descrambled signal, wherein the step of constructing said scrambling key comprises calculating the Y-intercept of the line formed on said Euclidean plane by said first, and said at least one additional share.