| 摘要 |
A user authentication judging device stores therein proper environment information considered appropriate for a use environment of an information processing device, and stores therein a proper environment judging threshold set for each piece of the proper environment information. If changed environment information collected by detecting a change in the use environment of the information processing device matches with any piece of the proper environment information, the user authentication judging device determines to authenticate the changed environment information, and if the collected changed environment information does not match with any piece of the proper environment information, the user authentication judging device does not determine to authenticate the changed environment information. If the changed environment information is authenticated, the user authentication judging device instructs reception of living body information from an applicant, and instructs setting of a proper environment judging threshold corresponding to the proper environment information matched with the changed environment information as an object to be compared with similarity calculated by performing verification. Upon receiving the living body information from the applicant, the user authentication judging device performs authentication judgment by verifying the living body information received from the applicant with registered living body information, by using the proper environment judging threshold set under instruction as an object to be compared with the similarity. |
