Patent ID: 7590247

Claim:
In an environment that includes a plurality of users, wherein a first user possesses a set of keys, said set of keys including a first key that enables secure communication among a set of users, said set of users including at least said first user and a second user, a computer-implemented keying method for execution with computer code embodied on a tangible computer readable medium, comprising: upon eviction of at least said second user, determining an updated first key using information that includes said first key and a second key, wherein said second key enables secure communication among a subgroup of said set of users, wherein said subgroup does not include users subject to said eviction; wherein said determining uses a function having the following properties: (1) knowledge of said updated first key does not give knowledge of said first key or said second key, (2) knowledge of said first key does not give any knowledge of said updated first key, and (3) knowledge of said first key and said updated first key does not give any knowledge of said second key; wherein said updated first key is equal to F(first key, second key), wherein F( ) is a one-way function; wherein said subgroup is a self-repairing group, each member of said subgroup capable of independently updating said first key, where said self-repairing uses a reusable power set, said reusable power set using a power set of said members as a basis for group key updates and including 2 N sets, where N includes the number of said members.