A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> In this paper we show the feasibility of template protecting biometric authentication systems. In particular, we apply template protection schemes to fingerprint data. Therefore we first make a fixed length representation of the fingerprint data by applying Gabor filtering. Next we introduce the reliable components scheme. In order to make a binary representation of the fingerprint images we extract and then quantize during the enrollment phase the reliable components with the highest signal to noise ratio. Finally, error correction coding is applied to the binary representation. It is shown that the scheme achieves an EER of approximately 4.2% with secret length of 40 bits in experiments. <s> BIB001 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> Within the next year, travelers from dozens of nations may be carrying a new form of passport in response to a mandate by the United States government. The e-passport, as it is sometimes called, represents a bold initiative in the deployment of two new technologies: Radio-Frequency Identification (RFID) and biometrics. Important in their own right, e-passports are also the harbinger of a wave of next-generation ID cards: several national governments plan to deploy identity cards integrating RFID and biometrics for domestic use. We explore the privacy and security implications of this impending worldwide experiment in next-generation authentication technology. We describe privacy and security issues that apply to e-passports, then analyze these issues in the context of the International Civil Aviation Organization (ICAO) standard for e-passports. <s> BIB002 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> Details multimodal biometrics and its exceptional utility for increasingly reliable human recognition systems. Reveals the substantial advantages of multimodal systems over conventional identification methods. <s> BIB003 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> In this paper, we propose a feature-level fusion approach for improving the efficiency of palmprint identification. Multiple elliptical Gabor filters with different orientations are employed to extract the phase information on a palmprint image, which is then merged according to a fusion rule to produce a single feature called the Fusion Code. The similarity of two Fusion Codes is measured by their normalized hamming distance. A dynamic threshold is used for the final decisions. A database containing 9599 palmprint images from 488 different palms is used to validate the performance of the proposed method. Comparing our previous non-fusion approach and the proposed method, improvement in verification and identification are ensured. <s> BIB004 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> With the pace of increasing online transactions and communication, the demand for security and privacy increases. To protect confidential information and to authenticate people electronically, several solutions already introduced. Traditional biometric systems that are based on single biometric usually suffer from problems like impostorspsila attack or hacking, unacceptable error rates. To improve security and privacy and systempsilas reliability two or more biometrics of the same identity could be combined in a method that enhances the efficiency of the system. The biometric information, however, is irreplaceable information, when it is compromised. Thereby, one must give a special attention to protection of such information. We propose a novel protection technique for the biometric information, especially the feature information and the templates. The point of our proposal is securely embeds and extracts an iris template in a fingerprint image using a combined DWT and LSB based biometric watermarking algorithm in each authentication. The embedded data travel through insecure communication line like the Internet, and they are used in matching process. This technique causes security against eavesdropping and replay attacks on the Internet, because the watermark embedded transmitted data are used in the authentication session after watermark extraction. <s> BIB005 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> Over the last two decades, in the field of secure communication and financial on-line applications, we have witnessed an explosive growth in biometric personal authentication systems which are covenant with a measurable physical characteristic or behavioral trait. On-line refers to making use of the time functions of the signing process. Verification of on-line signature as a biometric modality still is challenging fields of research, since the number of pointer based devices emerges as input devices for many e-commerce and m-commerce applications. The deployment of automatic handwritten signature verification with technology still remains open for novel methods due to inter-class and intra-class variations of signature. Since the area is currently one of the most on the go and the bulk of research is very large, this survey paper covers some of the examples of the ways. <s> BIB006 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> In this paper we present a novel on-line signature based biometric recognition system, where cryptographic techniques are employed to provide protection and cancelability to function based signature templates. The performances of the proposed protected on-line signature recognition system are evaluated on the public MCYT signature database, and compared with the performances achievable using unprotected approaches, as well as other signature template protection approaches. The reported results show that, when using the proposed cryptosystem, protected and renewable signature templates can be properly generated and used for recognition purposes. <s> BIB007 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> The term biometrics refers to “automated recognition of individuals based on their behavioral and biological characteristics” (ISO/IEC JTC1 SC37). Several physiological (static) as well as behavioral (non-static) biometric characteristics have been exploited (Jain, Flynn & Ross, 2008) such as fingerprints, iris, face, hand, voice, gait, keystroke dynamics, etc., depending on distinct types of applications (see Figure 1). Biometric traits are acquired applying adequate sensors and distinctive feature extractors are utilized in order to generate a biometric template (reference data) in the enrollment process. During verification (authentication process) or identification (identification can be handled as a sequence of biometric comparisons against the enrollment records in a reference databse) the system processes another biometric measurement from which an according template is extracted and compared against the stored template(s) yielding acceptance/ rejection or hit/ no-hit, respectively. The presented work is motivated by very recent advances in the fields of multi-biometric recognition (Ross et al., 2006) and biometric template protection (Rathgeb & Uhl, 2011). Automatic recognition systems based on a single biometric indicator often have to contend with unacceptable error rates (Ross & Jain, 2003). Multi-biometric systems have improved the accuracy and reliability of biometric systems (Ross et al., 2006). Biometric vendors are already deploying multi-biometric systems (e.g. fingerprint and finger vein by SAFRAN Morpho1) and multi-biometric recognition is performed on large-scale datasets (e.g. within the Aadhaar project (Unique Identification Authority of India, 2012) by the Unique Identification Authority of India (UIDAI)). However, security of multi-biometric templates is especially crucial as they contain information regarding multiple traits of the same subject (Nagar et al., 2012). The leakage of any kind of template information to unauthorized individuals constitutes serious security and privacy risks, e.g. permanent tracking of subjects without consent (Ratha et al., 2001) or reconstruction of original biometric traits (e.g. fingerprints (Cappelli et al., 2007) or iris textures (Venugopalan & Savvides, 2011)) might become a realistic threat. Therefore, biometric template protection technologies have been developed in order to protect privacy and integrity of stored biometric data. However, so far, template protection schemes which provide provable security/ privacy, and achieve practical recognition rates have remained elusive, even on small datasets. This bookchapter provides a comprehensive overview of <s> BIB008 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> In this correspondence, we analyze the vulnerabilities of biometric authentication protocols with respect to user and data privacy. The goal of an adversary in such context is not to bypass the authentication but to learn information either on biometric data or on users that are in the system. We elaborate our analysis on a general system model involving four logical entities (sensor, server, database, and matcher), and we focus on internal adversaries to encompass the situation where one or a combination of these entities would be malicious. Our goal is to emphasize that when going beyond the usual honest-but-curious assumption much more complex attacks can affect the privacy of data and users. On the one hand, we introduce a new comprehensive framework that encompasses the various schemes we want to look at. It presents a system model in which each internal entity or combination of entities is a potential attacker. Different attack goals are considered and resulting requirements on data flows are discussed. On the other hand, we develop different generic attacks. We follow a blackbox approach in which we consider components that perform operations on biometric data but where only the input/output behavior is analyzed. These attack strategies are exhibited on recent schemes such as the distributed protocol of Bringer (ACISP 2007), which is based on the Goldwasser-Micali cryptosystem, the related protocol of Barbosa (ACISP 2008), which uses the Paillier cryptosystem, and the scheme of Stoianov (SPIE 2010), that features the Blum-Goldwasser cryptosystem. All these schemes have been developed in the honest-but-curious adversary model and show potential weaknesses when considered in our malicious insider attack model. <s> BIB009 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> Recognizing people by their ear has recently received significant attention in the literature. Several reasons account for this trend: first, ear recognition does not suffer from some problems associated with other non-contact biometrics, such as face recognition; second, it is the most promising candidate for combination with the face in the context of multi-pose face recognition; and third, the ear can be used for human recognition in surveillance videos where the face may be occluded completely or in part. Further, the ear appears to degrade little with age. Even though current ear detection and recognition systems have reached a certain level of maturity, their success is limited to controlled indoor conditions. In addition to variation in illumination, other open research problems include hair occlusion, earprint forensics, ear symmetry, ear classification, and ear individuality. This article provides a detailed survey of research conducted in ear detection and recognition. It provides an up-to-date review of the existing literature revealing the current state-of-art for not only those who are working in this area but also for those who might exploit this new approach. Furthermore, it offers insights into some unsolved ear recognition problems as well as ear databases available for researchers. <s> BIB010 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> This chapter discusses the performance of five different iris segmentation algorithms on challenging periocular images. The goal is to convey some of the difficulties in localizing the iris structure in images of the eye characterized by variations in illumination, eyelid and eyelash occlusion, de-focus blur, motion blur, and low resolution. The five algorithms considered in this regard are based on the (a) integro-differential operator; (b) hough transform; (c) geodesic active contours; (d) active contours without edges ; and (e) directional ray detection method. Experiments on the Face and Ocular Challenge Series (FOCS) Database highlight the pros and cons of the individual segmentation algorithms. <s> BIB011 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> Smart environments established by the development of mobile technology have brought vast benefits to human being. However, authentication mechanisms on portable smart devices, particularly conventional biometric based approaches, still remain security and privacy concerns. These traditional systems are mostly based on pattern recognition and machine learning algorithms, wherein original biometric templates or extracted features are stored under unconcealed form for performing matching with a new biometric sample in the authentication phase. In this paper, we propose a novel gait based authentication using biometric cryptosystem to enhance the system security and user privacy on the smart phone. Extracted gait features are merely used to biometrically encrypt a cryptographic key which is acted as the authentication factor. Gait signals are acquired by using an inertial sensor named accelerometer in the mobile device and error correcting codes are adopted to deal with the natural variation of gait measurements. We evaluate our proposed system on a dataset consisting of gait samples of 34 volunteers. We achieved the lowest false acceptance rate (FAR) and false rejection rate (FRR) of 3.92% and 11.76%, respectively, in terms of key length of 50 bits. <s> BIB012 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> On 14th October 2013 the European Parliament Committee on Industry, Research and Energy (ITRE) paved the way on the regulation and harmonisation for electronic identification, authentication and trust services (eIDAS) between EU member states. This upcoming regulation will ensure mutual recognition and acceptance of electronic identification across borders, which also provides an opportunity to establish trusted electronic transactions in the Single Euro Payments Area (SEPA). The contribution of the presented paper is twofold: on the one hand we discuss the adaption of the upcoming eIDAS standard towards trusted banking transactions and outline resulting security and privacy enhancements; on the other hand we extend the eIDAS standard by biometric authenticated transactions which not only boost user convenience, trust and confidence towards eBanking and eBusiness, but suggest to integrate state-of-the-art privacy compliant biometric technologies into the security ecosystem, which is promoted by both, the European Payment Council (EPC) and the European Banking Union (EBU). As a result we identify eIDAS as highly suitable for banking transactions since it is solely based on security protocols and infrastructure which have been for more than ten years proven secure in the civil aviation domain. <s> BIB013 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> Recently, forensic science has had many challenges in many different types of crimes and crime scenes, vary from physical crimes to cyber or computer crimes. Accurate and efficient human identification or recognition have become crucial for forensic applications due to the large diversity of crime scenes, and because of the increasing need to accurately identify criminals from the available crime evidences. Biometrics is an emerging technology that provides accurate and highly secure personal identification and verification systems for civilian and forensic applications. The positive impact of biometric modalities on forensic science began with the rapid developments in computer science, computational intelligence, and computing approaches. These advancements have been reflected in the biometric modality capturing process, feature extraction, feature robustness, and features matching. A complete and automatic biometric identification or recognition systems have been built accordingly. This chapter presents a study of the impacts of using some biometric modalities in forensic applications. Although biometrics identification replaces human work with computerized and automatic systems in order to achieve better performance, new challenges have arisen. These challenges lie in biometric system reliability and accuracy, system response time, data mining and classification, and protecting user privacy. This chapter sheds light on the positive and the negative impacts of using some biometric modalities in forensic science. In particular, the impacts of fingerprint image, facial image, and iris patterns are considered. The selected modalities are covered preliminarily before tackling their impact on forensic applications. Furthermore, an extensive look at the future of biometric modalities deployment in forensic applications is covered as the last part of the chapter. <s> BIB014 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> In this paper, we propose a new finger multi-biometric cryptosystem using feature-level fusion to simultaneously protect multiple templates of fingerprint, finger vein, finger knuckle print and finger shape traits as a single secure sketch. We theoretically analyze the featurelevel fusion for finger multi-biometric cryptosystem with respect to their impact on security and recognition accuracy. The comparative experimental results ascertain that finger multibiometric cryptosystem outperforms the uni-biometric counterparts in terms of verification performance and template security. <s> BIB015 </s> A Survey on Multimodal Biometrics and the Protection of Their Templates <s> Biometric Template Protection <s> Multi-biometric systems are known to be universal and more accurate in biometric recognition. However, the storage of multiple biometric templates as separate entities pose major threats to user privacy and system security. Therefore, we propose to fuse multiple biometric modalities at the feature level in order to obtain an integrated template and to secure the fused templates using a hybrid template protection method. The proposed method is made out of a feature transformation technique known as Random Tiling and an equal-probable 2^N discretization scheme. The former enables the revocability of the template and the latter converts the feature elements into binary representations according to the area under the genuine interval curve, in order to offer better privacy protection to the template. Our experimental results show that the proposed multi-biometric template protection scheme demonstrates better verification results as compared to their unibiometric counterparts while preserving template security. <s> BIB016
Template Protection can be simply described as a straightforward and novel cryptographic construction. Biometrics can be found where personal information is employed to authenticate users, and here the readings are inherently noisy, not only because of their nature, but also, because of the pattern recognition techniques BIB012 BIB013 . However, such architectures have been used in a number of realworld, error-prone environments. Due to security concerns that arise from the storage of these data, several techniques  provide mechanisms, that can face the technical weaknesses of parameterization, representing a primitive with a special property of error-tolerance. The final aim is to improve the reliability of the systems and enlarge the chances for public acceptance and user confidence BIB007 . Categories. Biometric characteristics are largely immutable and any kind of compromise is undesirable BIB010 BIB001 . The standard encryption algorithms do not support a comparison of biometric templates in an encrypted domain, leaving important personal information totally exposed, during the authentication. While user authentication is based on possession of secret keys, key management is performed introducing another layer of authentication. In this way, encryption of data inherits the security of according biometrics applied to release correct decrypting keys. Biometric template protection schemes are usually categorised in two main groups and are designed to meet the requirements of biometric data protection BIB005 . Schematic illustration is shown in Fig. 1 . Cancelable Biometrics also referred to as feature transformations are designed in a way, that it should be computationally difficult to recover the original information BIB003  . The idea is to apply transformations that do not affect the elements, while are tolerant to variations. The basic fact, in this category, is that cancelable biometrics consist of intentional distortions of signals that are repeatedly transformed, similarly to those between templates in the transformed domain. Techniques of transformation modify the template in a user specific way. During authentication, the same transformation is applied to the biometric query, and the matching is performed in the already transformed area, so as to avoid the exposition of the original stored template BIB006 . A weak point of the system is that the transformation key is stored along with the biometric template. One solution for this can be the non-invertibility of the used transformation function, even in those cases, where the attacker knows the key. Furthermore, assuming beforehand that the transformed biometric data may be compromised, the parameters should be changed, in order to secure the template. Finally, to prevent the tracking subjects by cross-matching databases processes, recent studies have tested methods for applying different transformations for different applications BIB008 BIB014 . Cancelable biometrics are distinguished in two categories: non-invertible transforms and biometric salting. Academic research in this area consists of numerous works that can be further classified. It is worth mentioning that published works, in this area, apply the techniques of robust hashing systems and biohashing in specific modalities, studying the error rates, with remarkable results. These examinations also include analysis of the design from a constructional and security aspect, and evaluating the behavior of those schemes against potential attacks BIB011 . Biometric Cryptosystems are designed to securely bind a digital key to a biometric feature or generate a key from it. The idea, for a design of robust keys, started as a solution to threats like copying, sharing and distributing biometrics from the initial genuine storage. This is the reason for their second name, as helper data methods. Based on schemes which perform fuzzy comparisons, using decision thresholds, original templates are replaced through biometric-dependent public information. Specifically, secure sketches are derived from the biometric template after the enrollment process. This sketch is stored in the system, instead of the original template, in a form of a function. This mixture is obtained by binding the template with an error-correcting code, which itself is defined by a key. The strength, in terms of security, is the absence of the user's data, which however is a drawback for this design. Security relies on the difficulty to recover the template, using as attacks an authentication query or an error-correcting code. Some examples of biometric cryptosystems are fuzzy vault schemes, fuzzy extractors, and secret sharing approaches, secure sketches and others. Typically, these are separated into two main categories according to the schemes, as key-binding or key-generation BIB007 . Both technologies aimed to meet some requirements like non-invertibility where, given a protected template, it should be difficult for the attacker to find a biometric feature set that will match with the initial one. Second, we need revocability where versions of protected templates can be generated from the same biometric data and, concurrently, the protected templates should not allow crossmatching process, obeying to the necessity for diversity of data representations BIB002 . The use of these techniques can offer advantages, taking into account the uses cases, a fact that is also underlined in some published works BIB015 BIB016 BIB009  , where different approaches and combinations can be presented. In general, comparing the two methods of protection, cryptosystems tending to have stronger non-invertibility transformation schemes also offer unlinkability. Separately, or using hybrid products of their connection, several traditional attacks against systems have been prevented and the generated template is usually strong enough to be reconstructed, which is a feature that increases privacy and, consequently, the social acceptance BIB004 .