| 摘要 |
PROBLEM TO BE SOLVED: To provide a time authentication system, an apparatus, and a program capable of performing time authentication on a mobile terminal without requiring for using two-way communication for each time authentication and for the mediation of a certificate center at the certification of a time stamp. SOLUTION: The mobile terminal 10 generates a tentative time stamp S<SB>kts</SB>(h(f), id, t) and an approval signature S<SB>ksg</SB>(h(f)) on the basis of its internal clock 11 at the authentication of an electronic file f. A private key kts for generating the tentative time stamp is protected from unauthorized access by a tamper resistant protecting region 25. A certificate agency apparatus 30 issues a private key ksg for generating an approval signature after verification by the internal clock, and the private key can be used for different electronic files during validity depending on the time error of the internal clock itself and warrant the accuracy of time stamp time information. Thus, the two-way communication by each time authentication is not required. The tentative time stamp and the approval signature can be verified by a public key corresponding to the private key of the digital signature system. Thus, no verification center is required. The mobile terminal generates the tentative time stamp and the approval signature to perform time authentication. COPYRIGHT: (C)2007,JPO&INPIT
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