Abstract

Nowadays biometric authentication systems have been more developed, especially in secure and financial systems; so cracking a biometric authentication system is now a growing concern. But their security has not received enough attention. Imitating a biometric trait of a genuine user to deceive a system, spoofing, is the most important attacking method. Multi biometric systems have been developed to overcome some weaknesses of single biometric systems because the forger needs to imitate more than one trait. No research has further investigated the vulnerability of multimodal systems against spoof attack. We empirically examine the robustness of five fixed rules combining similarity scores of face and fingerprint traits in a bimodal system. By producing different spoof scores, the robustness of fixed combination rules is examined against various possibilities of spoofing. Robustness of a multi biometric system depends on the combination rule, the spoof trait and the intensity of spoofing. Min rule shows the most robustness when face is spoofed especially in very secure systems but when the fingerprint is faked the max rule shows the least vulnerability against possibilities of spoofing.