| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication device having a time authentication request function capable of reducing costs for reissuing a time stamp. SOLUTION: When a request program for reissuing the time stamp is executed periodically, and there is an e-document where the term of validity of the time stamp expires within a week, it is determined whether the time stamp should be reissued depending on whether the storage term of each e-document concerned has expired (steps 201-203). When the time stamp should be reissued and there are a plurality of documents whose term of storage does not expire in e-documents in which the term of validity in the time stamp expires within a week; the plurality of documents are put together, a hash value is calculated, and TSA is requested to reissue the time stamp (steps 204-208). COPYRIGHT: (C)2007,JPO&INPIT
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