Embedding Local Quality Measures in Minutiae-Based Biometric Recognition

Degradation in data quality is still a main source of errors in the modern biometric recognition systems. However, the data quality can be embedded in the recognition methods at global and local levels to build more accurate biometric systems. Local quality measures represent the quality of local parts within a biometric sample. They are either combined into a global quality measure or directly embedded into the recognition techniques. Minutiae-based comparison is the main and the most common technique used for fingerprint recognition and high-resolution palmprint recognition in various security and forensic applications. The focus of this thesis is mainly on direct incorporation of the local quality measures into the state-of-the-art minutiae-based recognition methods, particularly those based on Minutiae Cylinder-Code (MCC). Firstly, we introduce cylinder quality measures as a new type of local quality measures associated with the local minutiae descriptors. Then, we propose several methods for incorporating such local quality measures into the biometric systems, in order to improve their recognition performance. Among them is a novel and efficient quality-based consolidation method for embedding minutiae quality and cylinder quality measures in MCC based comparison methods. We also propose a supervised embedding method based on a binary classification model, which requires labeled minutiae for training. Finally, we apply a variant of the proposed consolidation method for the challenging case of latent fingerprint and palmprint identification with embedded subjective and objective minutiae quality.

Trustworthy Biometric Verification under Spoofing Attacks

Ivana Chingovska

The need for automation of the identity recognition process for a vast number of applications resulted in great advancement of biometric systems in the recent years. Yet, many studies indicate that these systems suffer from vulnerabilities to spoofing (presentation) attacks: a weakness that may compromise their usage in many cases. Face verification systems account for one of the most attractive spoofing targets, due to the easy access to face images of users, as well as the simplicity of the spoofing attack manufacturing process. Many counter-measures to spoofing have been proposed in the literature. They are based on different cues that are used to distinguish between real accesses and spoofing attacks. The task of detecting spoofing attacks is most often considered as a binary classification problem, with real accesses being the positive class and spoofing attacks being the negative class. The main objective of this thesis is to put the problem of anti-spoofing in a wider context, with an accent on its cooperation with a biometric verification system. In such a context, it is important to adopt an integrated perspective on biometric verification and anti-spoofing. In this thesis we identify and address three points where integration of the two systems is of interest. The first integration point is situated at input-level. At this point, we are concerned with providing a unified information that both verification and anti-spoofing systems use. The unified information includes the samples used to enroll clients in the system, as well as the identity claims of the client at query time. We design two anti-spoofing schemes, one with a generative and one with a discriminative approach, which we refer to as client-specific, as opposed to the traditional client-independent ones. The proposed methods are applied on several case studies for the face mode. Overall, the experimental results prove the integration to be beneficial for creating trustworthy face verification systems. At input-level, the results show the advantage of the client-specific approaches over the client-independent ones. At output-level, they present a comparison of the fusion methods. The case studies are furthermore used to demonstrate the EPS framework and its potential in evaluation of biometric verification systems under spoofing attacks. The source code for the full set of methods is available as free software, as a satellite package to the free signal processing and machine learning toolbox Bob. It can be used to reproduce the results of the face mode case studies presented in this thesis, as well as to perform additional analysis and improve the proposed methods. Furthermore, it can be used to design case studies applying the proposed methods to other biometric modes. At the second integration point, situated at output-level, we address the issue of combining the output of biometric verification and anti-spoofing systems in order to achieve an optimal combined decision about an input sample. We adopt a multiple expert fusion approach and we investigate several fusion methods, comparing the verification performance and robustness to spoofing of the fused systems. The third integration point is associated with the evaluation process. The integrated perspective implies three types of inputs for the biometric system: real accesses, zero-effort impostors and spoofing attacks. We propose an evaluation methodology for biometric verification systems under spoofing attacks, called Expected Performance and Spoofability (EPS) framework, which accounts for all the three types of input and the error rates associated with them. Within this framework, we propose the EPS Curve (EPSC), which enables unbiased comparison of systems.

EPFL2016

On Effectiveness of Anomaly Detection Approaches against Unseen Presentation Attacks in Face Anti-Spoofing

André Anjos, Sébastien Marcel, Amir Mohammadi

While face recognition systems got a significant boost in terms of recognition performance in recent years, they are known to be vulnerable to presentation attacks. Up to date, most of the research in the field of face anti-spoofing or presentation attack detection was considered as a two-class classification task: features of bona-fide samples versus features coming from spoofing attempts. The main focus has been on boosting the anti-spoofing performance for databases with identical types of attacks across both training and evaluation subsets. However, in realistic applications the types of attacks are likely to be unknown, potentially occupying a broad space in the feature domain. Therefore, a failure to generalize on unseen types of attacks is one of the main potential challenges in existing anti-spoofing approaches. First, to demonstrate the generalization issues of two-class anti-spoofing systems we establish new evaluation protocols for existing publicly available databases. Second, to unite the data collection efforts of various institutions we introduce a challenging Aggregated database composed of 3 publicly available datasets: Replay-Attack, Replay-Mobile and MSU MFSD, reporting the performance on it. Third, considering existing limitations we propose a number of systems approaching a task of presentation attack detection as an anomaly detection, or a one-class classification problem, using only bona-fide features in the training stage. Using less training data, hence requiring less effort in the data collection, the introduced approach demonstrates a better generalization properties against previously unseen types of attacks on the proposed Aggregated database.

2018

Anti-spoofing in action: joint operation with a verification system

André Anjos, Ivana Chingovska, Sébastien Marcel

Besides the recognition task, today's biometric systems need to cope with additional problem: spoofing attacks. Up to date, academic research considers spoofing as a binary classification problem: systems are trained to discriminate between real accesses and attacks. However, spoofing counter-measures are not designated to operate stand-alone, but as a part of a recognition system they will protect. In this paper, we study techniques for decision-level and score-level fusion to integrate a recognition and anti-spoofing systems, using an open-source framework that handles the ternary classification problem (clients, impostors and attacks) transparently. By doing so, we are able to report the impact of different spoofing counter-measures, fusion techniques and thresholding on the overall performance of the final recognition system. For a specific use-case covering face verification, experiments show to what extent simple fusion improves the trustworthiness of the system when exposed to spoofing attacks.

2013

Trustworthy Biometric Verification under Spoofing Attacks

Ivana Chingovska

EPFL2016