Empirical evaluation of combining unobtrusiveness and security requirements in multimodal biometric systems

Unobtrusive user authentication is more convenient than explicit interaction and can also increase system security because it can be performed frequently, unlike the current "once explicitly and for a long time" practice. Existing unobtrusive biometrics (e.g., face, voice, gait) do not perform sufficiently well for high-security applications, however, while reliable biometric authentication (e.g., fingerprint or iris) requires explicit user interaction. This work presents experiments with a cascaded multimodal biometric system, which first performs unobtrusive user authentication and requires explicit interaction only when the unobtrusive authentication fails. Experimental results obtained for a database of 150 users show that even with a fairly low performance of unobtrusive modalities (Equal Error Rate above 10%), the cascaded system is capable of satisfying a security requirement of a False Acceptance Rate less than 0.1% with an overall False Rejection Rate of less than 0.2%, while authenticating unobtrusively in 65% of cases.