CONTROLLED ACCESS DISTRIBUTION METHOD BY OVERLAPPING SUBSETS OF USERS AND ASSOCIATED RECEPTION METHOD

Abstract

CONTROLLED ACCESS BROADCASTING METHOD BY OVERLAPPING USER SUBSETS AND ASSOCIATED RECEPTION METHOD The present invention relates to a controlled access data broadcasting method by overlapping user subsets, said subsets belonging to a pre-established family () of subsets indexed according to an order relation, each subset () of said family being associated with an encryption key (), in which a data broadcasting center determines (410) the subsets () of said family allowing an overlapping () of the users authorized to access this data and of these only, this method using a message header with an economical encoding of the tuple of indices () of the subsets by means of a codeword () of bits. The present invention also relates to a method of receiving a broadcast message () using the aforementioned data broadcasting method. Figure for abstract: Fig. 4