Patent ID: 7738662
Filing Date: 2010-06-15
Classification: G06F,G11B,H04L

Abstract:
1. An information processing system comprising: A) a key distribution center (KDC) adapted to produce and issue an enabling key block (EKB), the KDC having an EKB type definition list representing a correspondence for the EKB, in which the EKB is produced based on a key tree and device keys; the 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, wherein the leaves correspond to a plurality of devices; the enabling key block (EKB) including a plurality of encrypted key data, the encrypted key data being produced by encrypting a key based on the device keys assigned to the root, to at least some of the leaves or to at least some of the nodes, wherein the encrypted key data in EKB is used for decoding an encrypted content key; and B) at least one EKB requester adapted to request a EKB to the key distribution center, wherein the KDC is operable to send a notification to the EKB requester, wherein the notification indicates a change in state of EKB.