User authentication apparatus and recording media

Abstract

A user authentication apparatus includes a photographing unit which photographs a two-dimensional code displayed on a user authentication support terminal, wherein the two-dimensional code is formed by encoding at least first identification information that uniquely identifies the user, and second identification information that uniquely identifies all user authentication performed using the user authentication support terminal collectively, into the two-dimensional code, an authentication factor acquisition unit which acquires an authentication factor, a decoding unit which acquires the first identification information and the second identification information by decoding the two-dimensional code, a first identification information inquiry unit which inquires as to an existence of the first identification information by referring to a storage unit, a second identification information collation unit which, when the inquiry issued by the first identification information inquiry unit is successful, reads from the storage unit the second identification information and collates the second identification information acquired by the decoding unit with the second identification information read from the storage unit, an authentication factor collation unit which, when the inquiry issued by the first identification information inquiry unit is successful, reads from the storage unit the authentication factor and collates the authentication factor acquired by the authentication factor acquisition unit with the authentication factor read from the storage unit, and a determination unit which determines that authentication of the user has been performed successfully when the collation performed by both the second identification information collation unit and the authentication factor collation unit are successful.