AUTHENTICATION SYSTEM, AUTHENTICATION DEVICE, AUTHENTICATION METHOD, AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To perform authentication using different authentication information each time without exchanging information required for generating authentication information at every authentication.SOLUTION: A user terminal 1 acquires authentication device time information indicating the time of a clock installed in an authentication device 2, and generates time difference information indicating time difference between the time which is indicated by the acquired authentication device time information and the time which is acquired from a clock installed in the user terminal 1 when the authentication device time information is acquired. When the user terminal 1 requires service from a service providing device 3, the user terminal 1 corrects the time acquired from the clock installed in the user terminal 1 on the basis of the time difference information, generates encrypted authentication information including the corrected time, and transmits the authentication information to the service providing device 3. The authentication device 2 acquires the time corrected by the user terminal 1 by decrypting the authentication information received by the service providing device 3, and determines that authentication is successful if the difference between the corrected time and the time acquired from the clock installed in the authentication device 2 is within a predetermined range.