The present invention relates to a key management method to establish selective secret information in multiple disjoint groups, more specifically to a method of reducing the broadcast size in access hierarchies and localize and facilitate management in said access hierarchies. The key management method selects a number of subgroups. Each subgroup supports an instance of a key distribution method for receiving distributed key material, and is capable of computing a usage security key based on the distributed key material and predefined user group key material.