INFORMATION PROCESSING UNIT, TERMINAL UNIT, INFORMATION PROCESSING METHOD, KEY GENERATION METHOD AND PROGRAM

摘要

There is provided an information processing unit enabling reduction of the number of keys to be held by a terminal unit and the amount of calculations necessary for decryption of encrypted data. The information processing unit configures an entire binary tree made up of n-number of leaf nodes, a root node and a plurality of intermediate nodes different from the root node and the leaf nodes and divides the entire tree into a plurality of base subtrees including n1/y number of leaf nodes to form a y-level (y is a divisor of log(n)) hierarchical structure, such that root nodes of the base subtrees at a lower level coincide with leaf nodes of the base subtree at an upper level. Further, it assigns subsets of the terminal units to nodes of the respective base subtrees and generates directed graphs where directed edges connecting coordinate points on a coordinate axis are set.