Presentation attack (spoofing) detection (PAD) typically operates alongside biometric verification to improve reliablity in the face of spoofing attacks. Even though the two sub-systems operate in tandem to solve the single task of reliable biometric verification, they address different detection tasks and are hence typically evaluated separately. Evidence shows that this approach is suboptimal. We introduce a new metric for the joint evaluation of PAD solutions operating in situ with biometric verification. In contrast to the tandem detection cost function proposed recently, the new tandem equal error rate (t-EER) is parameter free. The combination of two classifiers nonetheless leads to a \emph{set} of operating points at which false alarm and miss rates are equal and also dependent upon the prevalence of attacks. We therefore introduce the \emph{concurrent} t-EER, a unique operating point which is invariable to the prevalence of attacks. Using both modality (and even application) agnostic simulated scores, as well as real scores for a voice biometrics application, we demonstrate application of the t-EER to a wide range of biometric system evaluations under attack. The proposed approach is a strong candidate metric for the tandem evaluation of PAD systems and biometric comparators.

翻译：摘要：呈现攻击（欺骗）检测（PAD）通常与生物特征验证协同工作，以提高面对欺骗攻击时的可靠性。尽管这两个子系统协同解决生物特征验证这一单一任务，但它们针对不同的检测任务，因此通常被分开评估。证据表明这种方法并非最优。我们提出了一种新指标，用于对与生物特征验证协同运行的PAD解决方案进行联合评估。与近期提出的级联检测代价函数不同，新型级联等错误率（t-EER）无需参数设置。然而，两个分类器的组合会导致一组工作点，在这些点上虚警率和漏报率相等，且依赖于攻击的普遍性。因此，我们引入了并发t-EER，这是一个对攻击普遍性不变的唯一工作点。利用模态（甚至应用）无关的模拟分数以及语音生物特征应用的真实分数，我们展示了t-EER在受攻击生物特征系统评估中的广泛应用性。所提出的方法是PAD系统与生物特征比较器级联评估的一个有力候选指标。