| 摘要 |
PROBLEM TO BE SOLVED: To prevent fake attacks and resend attach without using a two-way communication and to verify the validity of location information. SOLUTION: A mobile terminal 10 uses unidirectional communication, and an authentication code verification section 17 verifies an authentication code, included in received information to prevent fake attacks. If optimal location information of the present device is contained in a triangular inside region, constituted of three broadcast station location information items among broadcast station location information on respective broadcast stations, the optimal location information which is calculated by using broadcast time information, broadcast station location information, time information of an internal clock, in a tamper-resistant protection region within the present device and an upper limit value of a positioning error determined, while taking into account the measured results, and the like, beforehand, and an inclusive error for the optimal location information is estimated within a preset error allowable range, a location information verification section 19 determines that a radio wave broadcast is not resent to prevent the resend attack. Accordingly, solution is obtained. COPYRIGHT: (C)2008,JPO&INPIT
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