INFORMATION PROCESSING SYSTEM AND METHOD USING CRYPTOGRAPHIC KEY BLOCK AND PROGRAM PROVIDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To realize information processing system and method capable of dividing the key tree configuration of a hierarchical structure and managing the key tree configuration. SOLUTION: This system sets a plurality of entities which manages a sub tree as a partial tree constituting a key tree obtained by making each key correspond to routes, nodes and leaves on paths from the root of the tree to leaf constructed with a plurality of devices as leaves and generates a sub effective key block(sub EKB) on the basis of only a key set by being associated with a node or a leaf belonging to the sub tree and generates and distributes an effective key block(EKB) that can be decoded only in a selected entity by using the sub effective key block(EKB) generated by a plurality of entities.