Authenticated group key distribution scheme for a large distributed network

The authors propose a decentralized key distribution scheme. In this scheme, there are as many local key centers as needed and each user needs to select a key center at which to register when first joining the network. The most significant feature of the method is that each center needs only a single secret key. All personal keys that it needs for delivering encrypted keys to groups of users can be derived from this single key through a one-way function