US Patent 11991180 Authentication system, authentication device, authentication method and program

An authentication system, including at least one processor configured to: perform, based on a similarity between input authentication information that has been input and registered authentication information that has been registered, authentication of a user to be authenticated; determine whether there is a possibility that the user is authenticated as another user; acquire, when it is determined that there is the possibility that the user is authenticated as another user, for the input authentication information, a plurality of pieces of processed authentication information processed differently from each other; and determine, when it is determined that there is the possibility that the user is authenticated as another user, whether a predetermined number or more of pieces of processed authentication information are more similar to the registered authentication information than to the input authentication information and perform the authentication based on a result of the determination.