Key providing system, terminal device, and information processing method

摘要

A terminal device improved with a digraph generation method in a key distribution method of various types of broadcast encryption systems is provided. The terminal device includes an acquiring unit for acquiring information related to a set, which is selected from a plurality of sets representing a combination of a plurality of terminal devices, and which represents some or all of the plurality of terminal devices; an extracting unit for extracting the set contained in the information and to which it belongs; and a digraph generation unit for generating a directional branch for generating a key corresponding to the extracted set in a predetermined digraph formed by a plurality of directional branches.