Fingerprint authentication method and system for rejecting spoof attempts

A method of authenticating a user by means of a fingerprint authentication system comprising a finger sensing arrangement, comprising the following steps for each authentication attempt in a sequence of authentication attempts: receiving a touch by a candidate finger probe on the finger sensing arrangement; acquiring a candidate fingerprint image of the candidate finger probe; determining an authentication representation based on the candidate fingerprint image; retrieving a stored enrollment representation of an enrolled fingerprint of the user; determining a match score based on a comparison between the authentication representation and the enrolment representation; determining a liveness score for the authentication attempt; determining a qualification metric for the authentication attempt based on a relation between the liveness score for the authentication attempt and a liveness score for at least one previous authentication attempt; and determining an authentication result for the authentication attempt based on the match score, and the qualification metric.