| 摘要 |
PROBLEM TO BE SOLVED: To deal with an increase in traffic or an increase in internal resource consumption of related devices when a document creation unit utilizes a time stamp for an electronic document containing a plurality of pieces of time information, such as a log document. SOLUTION: A document creation unit 1 calculates a hash value of each software piece therein when it starts operation, and stores the hash value in a hash value holder 71 and a measurement log document holder 44. The document creation unit 1 accesses a time distribution unit plural times to receive time information therefrom, and records the time information in a log document and a measurement log document. The document creation unit 1 transmits the log document, the measurement log document, and digital signature-embedded hash value information (a measurement auxiliary document) in a tamper-resistant device 63 to a document receiving device. The document receiving device verifies matching of the hash values or digital signature in the document group, confirms software operating environments in the document creation unit 1 from the hash values, and determines whether the time information is correctly managed in the unit 1. COPYRIGHT: (C)2009,JPO&INPIT
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