BIOMETRIC AUTHENTICATION DEVICE, BIOMETRIC AUTHENTICATION METHOD, AND COMPUTER PROGRAM FOR BIOMETRIC AUTHENTICATION

A biometric authentication device including: a biometric information acquiring unit which generates a plurality of partial images, each of the partial images capturing a portion of biometric information of a user different from each other; a storage unit which stores data concerning registered biometric information of a registered user; a correlation value calculation unit which calculates the correlation value between a portion of biometric information represented on one partial image and the registered biometric information; a partial similarity update unit which, based on the correlation value for the one partial image and the correlation value for at least one other partial image acquired before the one partial image, updates partial similarity representing the degree of similarity between the registered biometric information and portions of biometric information represented on the one partial image and the at least one other partial image; an authentication unit which authenticates, when the partial similarity is equal to or higher than an authentication judging threshold, the user as the registered user; and an image loading unit which loads the next partial image of the one partial image from the biometric information acquiring unit when the partial similarity is lower than an authentication judging threshold.