Patent ID: 7346170
Filing Date: 2008-03-18
Classification: G11B,H04L

Abstract:
1. An information processing system, comprising: a key tree including a plurality of leaves, a root, and a plurality of nodes existing in paths from the plurality of leaves to the root; a plurality of devices assigned to at least some of the leaves; a plurality of keys assigned to the root, to at least some of the leaves and to at least some of the nodes; an enabling key block (EKB) including encrypted data produced by selecting one of the paths in the key tree and encrypting a higher-level key in the selected path using a lower-level key in the selected path such that the encrypted data can be decrypted only by a selected one of the plurality of devices capable of using a node key set corresponding to the selected path, the EKB being provided to the selected device; an EKB requester operable to issue an EKB production request selected from the group consisting of a key distribution center (KDC) operable to receive the EKB production request, to generate the EKB including the already-produced root key in response to the first EKB production request, and to generate the EKB including the new root key in response to the second EKB production request; at least one category entity, wherein the key tree further includes a plurality of sub-trees serving as category trees that are grouped in accordance with categories and managed by the at least one category entity; and the EKB requester is operable to select an EKB type identifier for identifying an EKB type, the EKB type identifier being selected on the basis of an EKB type definition list representing a correspondence between the EKB type identifier and identification data capable of identifying at least one of the category trees that is operable to process EKBs of the EKB type identified by the EKB type identifier, and to output, as the first or the second EKB production request, the EKB production request including the selected EKB type identifier, wherein the EKB type definition list is acquired from a storage means or an accessible site on a network.