| 摘要 |
PROBLEM TO BE SOLVED: To encrypt a part of a document or a moving picture, to make encrypted state sustain for a predetermined period, and to permit decryption when it becomes unnecessary to sustain secrecy. SOLUTION: In a document, secrecy sustention term of the region of a region identification information "Area1" is set at 2005/12/1, secrecy sustention term of the region "Area2" is set at 2005/12/30, and secrecy holding period for the region "Area3" is set at 2005/12/15. Since the period for sustaining encryption state is set for the document and a client unit cannot decrypt that region for a predetermined period, secrecy can be sustained during that period. Furthermore, since similar processings can be performed even for an object shown in a moving picture, objects that permit decryption can be increases as the time elapses. COPYRIGHT: (C)2007,JPO&INPIT
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