Patent ID: 7356149

Claim:
An information processing method of receiving image data compression-coded for each spatial rectangle region and encrypting the image data, comprising: repeatedly forming one spatial rectangle region group from a plurality of adjacent spatial rectangle regions in an image space and another spatial rectangle region group from adjacent spatial rectangle region groups so as to define a hierarchical structure of the spatial rectangle region groups; assigning identification information uniquely identifying each node to each node in the hierarchal structure; generating encryption key information of an uppermost layer for an entire image expressed by encoded data; executing, up to a node located at a terminal, processing for generating encryption key information for a node of interest on the basis of encryption key information generated for a node located at an upper layer in the hierarchical structure, the identification information assigned to the node of interest, and a one-way function, so as to generate encryption keys for each spatial rectangle region; designating a desired spatial rectangle region group in a desired layer as an object to be encrypted in a tree structure of the spatial rectangle region groups; and executing encryption processing for each spatial rectangle region, each of which is located at a lower layer belonging to the designated spatial rectangle region group, by using an encryption key generated for each spatial rectangle region.