| 摘要 |
PROBLEM TO BE SOLVED: To reduce a risk of an illegal use attributable to a password that is known to other persons. ! SOLUTION: A user authentication system includes: a storage unit 94 that accumulates utilization information on each user as utilization history information to store the utilization history information; an extraction unit 92 that identifies any of users as an authenticated person, identifies the utilization information on a case high in a utilization frequency of the authenticated person as corresponding utilization information, and extracts one to a plurality of corresponding utilization information from the utilization history information stored in the storage unit; and an authentication unit 93 that, when authenticating the authenticated person, enables the authenticated person to select one to a plurality of dummy information and one to the plurality of corresponding utilization information extracted by the extraction unit in a state where the dummy information and the corresponding uti |
