Patent ID: 8594334

Claim:
A key management method wherein a number of user subgroups is selected, from a plurality G m of user groups each supporting an instance of a key distribution method M for receiving distributed key material, wherein each subgroup is capable of computing a usage security key based on the distributed key material and pre-defined user group key material and wherein the usage security key for users in the subgroup is generated, broadcasted and used according to the following steps: distributing, to each user entitled to a usage security key K i , a long term secret L i,m ; broadcasting, according to a key distribution method M, an instance j of a group key K G m ,j to each user in group G m ; a user i in group G m computing an instance K i,j of the usage security key K i , as a function of L i,m and K G m ,j ; and user i using the usage security key K i,j for processing information.