Patent ID: 7043024

Claim:
A method for reducing bandwidth needed to transmit key update information for a plurality of members forming a group, comprising: (a) associating a subgroup of said group with a leaf node of a hierarchical tree, said leaf node having associated therewith a leaf key common to members of said subgroup, wherein upon eviction of at least one member of said group, said leaf key enables said members of said subgroup to receive an update message for an interior node above said leaf node; wherein said subgroup is a self-repairing group, said self-repairing group being operative to update said leaf key independently; wherein each of said members of said subgroup is capable of independently updating a shared interior node key; wherein said self-repairing uses a reusable power set; wherein said reusable power set uses a power set of said members in said subgroup as a basis for group key updates; wherein said reusable power set includes 2 N sets, where N includes the number of said members.