Patent ID: 7269257
Filing Date: 2007-09-11
Classification: G11B,H04L

Abstract:
1. An information processing system using an encryption key block which constitutes a key tree in which respective keys are corresponded to a root, nodes and leaves on a path from the root to the leaves of a tree in which a plurality of devices are constituted as the leaves, executes renewal of keys on a selected path by selecting the path constituting the key tree and encryption processing of a superordinate key by a subordinate key and generates an enabling key block (EKB) to provide it to a device, the system comprising: a plurality of entities which constitute a part of the key tree, manage sub-trees classified based on capability as data processing ability of the devices, and generate a sub-enabling key block (sub-EKB) based only on a key set corresponding to nodes or leaves included in the sub-tree; and a key distribution center (KDC) which manages capability information of the plurality of entities and generates the enabling key block (EKB) decodable only by the entities having common capability by using the sub-enabling key block (sub-EKB) generated by the entities having the common capability.