1. An apparatus for authenticating a user by employing feature points of a fingerprint image of the user, comprising: a fingerprint image input circuit for scanning a fingerprint of a user to be registered, thereby providing a first fingerprint image and scanning a fingerprint of a user to be authenticated, thereby providing a second fingerprint image; a host circuit for providing data for feature points of the first fingerprint image having been registered as registered feature points data corresponding to the first fingerprint image and data for feature points of the second fingerprint image to be authenticated as target feature points data corresponding to the second fingerprint image; a security token circuit for estimating a position difference and a direction difference between pairs of a registered feature point and a target feature point and correcting the two feature points based on the position difference and the direction difference to thereby provide authentication result data to the host circuit; and an I/O interfacing circuit for performing interfacing fingerprint images between the fingerprint image input circuit and the host circuit and feature points data and authentication result data between the host circuit and the security token circuit.