Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> Because biometrics-based authentication offers several advantages over other authentication methods, there has been a significant surge in the use of biometrics for user authentication in recent years. It is important that such biometrics-based authentication systems be designed to withstand attacks when employed in security-critical applications, especially in unattended remote applications such as e-commerce. In this paper we outline the inherent strengths of biometrics-based authentication, identify the weak links in systems employing biometrics-based authentication, and present new solutions for eliminating some of these weak links. Although, for illustration purposes, fingerprint authentication is used throughout, our analysis extends to other biometrics-based methods. <s> BIB001 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> Biometrics-based authentication systems offer obvious usability advantages over traditional password and token-based authentication schemes. However, biometrics raises several privacy concerns. A biometric is permanently associated with a user and cannot be changed. Hence, if a biometric identifier is compromised, it is lost forever and possibly for every application where the biometric is used. Moreover, if the same biometric is used in multiple applications, a user can potentially be tracked from one application to the next by cross-matching biometric databases. In this paper, we demonstrate several methods to generate multiple cancelable identifiers from fingerprint images to overcome these problems. In essence, a user can be given as many biometric identifiers as needed by issuing a new transformation "key". The identifiers can be cancelled and replaced when compromised. We empirically compare the performance of several algorithms such as Cartesian, polar, and surface folding transformations of the minutiae positions. It is demonstrated through multiple experiments that we can achieve revocability and prevent cross-matching of biometric databases. It is also shown that the transforms are noninvertible by demonstrating that it is computationally as hard to recover the original biometric identifier from a transformed version as by randomly guessing. Based on these empirical results and a theoretical analysis we conclude that feature-level cancelable biometric construction is practicable in large biometric deployments <s> BIB002 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> To replace compromised biometric templates, cancelable biometrics has recently been introduced. The concept is to transform a biometric signal or feature into a new one for enrollment and matching. For making cancelable fingerprint templates, previous approaches used either the relative position of a minutia to a core point or the absolute position of a minutia in a given fingerprint image. Thus, a query fingerprint is required to be accurately aligned to the enrolled fingerprint in order to obtain identically transformed minutiae. In this paper, we propose a new method for making cancelable fingerprint templates that do not require alignment. For each minutia, a rotation and translation invariant value is computed from the orientation information of neighboring local regions around the minutia. The invariant value is used as the input to two changing functions that output two values for the translational and rotational movements of the original minutia, respectively, in the cancelable template. When a template is compromised, it is replaced by a new one generated by different changing functions. Our approach preserves the original geometric relationships (translation and rotation) between the enrolled and query templates after they are transformed. Therefore, the transformed templates can be used to verify a person without requiring alignment of the input fingerprint images. In our experiments, we evaluated the proposed method in terms of two criteria: performance and changeability. When evaluating the performance, we examined how verification accuracy varied as the transformed templates were used for matching. When evaluating the changeability, we measured the dissimilarities between the original and transformed templates, and between two differently transformed templates, which were obtained from the same original fingerprint. The experimental results show that the two criteria mutually affect each other and can be controlled by varying the control parameters of the changing functions. <s> BIB003 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> This paper presents an approach to generate secure minutiae information in fingerprint templates. Using triplets of minutia points, useful geometrical properties can be derived from minutia triplets to hide their coordinates, direction of minutia, and scale. This non-invertible transform enables matching from the results in the anonymous domain to fight against malicious attacks to biometrics. The goal is to achieve non-invertibility of the transformed templates without loss of discriminating capability. Proposed features can match two templates without alignment under low time complexity and memory requirement. The proposed approach is proven effective using the FVC2002 database to compare matching performances. The best result shows 3.61% of equal-error rate for the database DB2_A. <s> BIB004 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> Biometric template protection is an important issue to be resolved so that practical biometric authentication systems can be deployed. In this paper, we propose a non-invertible transform to perpendicularly project the distances between a pair of minutiae to a circle to generate the features. To achieve good performance, other local features such as relative angles between the minutiae pair, and global features such as orientation, ridge frequency and total number of minutiae of the randomly sampled blocks around each minutia are also utilized. The cancelable templates are eventually generated by the proposed “Bin-based Quantization (BQ)”. Both feature extraction and cancelable template generation are governed by a secret key to guarantee revocability and security. Experimental results conducted on FVC 2002 data set demonstrate the reasonable good performance of the proposed scheme. <s> BIB005 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> Biometrie authentication systems can address the problems of genuine user verification and usability suffered by the conventional cryptosystems based on the password and token. However, as biometrics is not replaceable, its privacy has become a concern. Also, if the same biometrics is used in multiple applications, it will be vulnerable to potential cross-matching attacks. In this paper, a projection line method is proposed for cancelable fingerprint template design. The main advantage of this method is its simplicity. Because there exist many possibilities projecting minutia into the projection line controlled by the whole range of possible projection line properties, the proposed approach offers non-invertible transformation and also possess good revocability property. <s> BIB006 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> In this paper, we introduce the Minutia Cylinder-Code (MCC): a novel representation based on 3D data structures (called cylinders), built from minutiae distances and angles. The cylinders can be created starting from a subset of the mandatory features (minutiae position and direction) defined by standards like ISO/IEC 19794-2 (2005). Thanks to the cylinder invariance, fixed-length, and bit-oriented coding, some simple but very effective metrics can be defined to compute local similarities and to consolidate them into a global score. Extensive experiments over FVC2006 databases prove the superiority of MCC with respect to three well-known techniques and demonstrate the feasibility of obtaining a very effective (and interoperable) fingerprint recognition implementation for light architectures. <s> BIB007 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> Cancelable biometrics has become an indispensable technique during biometric authentication. There have been several prior attempts to construct cancelable fingerprint templates. However, existing schemes have not provided a satisfying trade off between performance and security. In this paper, we proposed two novel approaches to construct registration-free cancelable fingerprint templates based on Minutia Cylinder Code, which is the state of the art local representation for fingerprint. And experiments show that the two approaches provide good results in terms of three criteria: performance, unlinkability and irreversibility. <s> BIB008 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> Minutia Cylinder-Code (MCC) is an effective representation for robust and fast fingerprint matching. To avoid that MCC templates can disclose sensitive information about position and angle of minutiae, a protected MCC representation was recently introduced (called P-MCC). In spite of a satisfactory level of accuracy and irreversibility, P-MCC templates cannot be revoked. In this paper we propose a two-factor protection scheme that makes P-MCC templates revocable. <s> BIB009 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> Abstract As an important biometric template protection technique, cancelable biometrics provides enhanced security for biometric-based authentication. Representing biometric information in binary form is useful in biometric template protection because it offers simplicity in feature representation and provides benefits in matching and storage. Therefore, it is no surprise that cancelable biometrics often exploits binary biometric representations as resultant templates. However, very often such binary biometric representations contained in cancelable biometrics have security shortfalls, because once they are compromised, the biometric features that they represent are likely to be retrieved. In this paper we propose an efficient non-invertible transformation – the partial Hadamard transform to securely protect binary biometric representations in the design of cancelable biometrics. When this non-invertible transform is applied to the DFT of the binary biometric representations, the resultant templates are complex vectors, from which the original binary vectors cannot be restored. A prominent feature of the proposed approach is that it preserves the stochastic distance between binary vectors after the transformation. This stochastic distance preserving property is theoretically proved and further demonstrated and verified by experiments. The cancelable fingerprint templates designed by the proposed partial Hadamard transform meet the requirements of revocability, diversity, non-invertibility and performance. Matching performance of the designed cancelable templates compares favorably with state-of-the-art methods that also involve binary biometric representations; for example, the Equal Error Rate of the proposed method in the lost-token scenario is 1% for FVC2002 DB1, 2% for FVC2002 DB2 and 5.2% for FVC2002 DB3. <s> BIB010 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> This study presents a protection method for fingerprint templates by using fused structures at the feature level. The authors compute two transformed features from minutiae points: namely, local structure and distant structure. These structures are represented as bit-strings. A fusion on bit-strings is done at the feature level to produce a cancelable template. An equal error rate (EER) of 2.19, 1.6 and 6.14% on Fingerprint Verification Competition (FVC) 2002 Database (DB)1 through DB3 databases and an EER of 11.89, 12.71, 17.6% on FVC 2004 DB1 through DB3 proves the tenability of the proposed method. <s> BIB011 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> A number of personal devices, such as smartphones, have incorporated fingerprint recognition solutions for user authentication purposes. This work proposes a dual-factor fingerprint matching scheme based on P-MCCs (Protected Minutia Cylinder-Codes) generated from fingerprint images and PUFs (Physically Unclonable Functions) generated from device SRAMs (Static Random Access Memories). Combining the fingerprint identifier with the device identifier results in a secure template satisfying the discriminability, irreversibility, revocability, and unlinkability properties, which are strongly desired for data privacy and security. Experiments convey the benefits of the proposed dual-factor authentication mechanism in enhancing the security of personal devices that utilize biometric authentication schemes. <s> BIB012 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> Smart mobile devices are playing a more and more important role in our daily life. Cancelable biometrics is a promising mechanism to provide authentication to mobile devices and protect biometric templates by applying a noninvertible transformation to raw biometric data. However, the negative effect of nonlinear distortion will usually degrade the matching performance significantly, which is a nontrivial factor when designing a cancelable template. Moreover, the attacks via record multiplicity (ARM) present a threat to the existing cancelable biometrics, which is still a challenging open issue. To address these problems, in this paper, we propose a new cancelable fingerprint template which can not only mitigate the negative effect of nonlinear distortion by combining multiple feature sets, but also defeat the ARM attack through a proposed feature decorrelation algorithm. Our work is a new contribution to the design of cancelable biometrics with a concrete method against the ARM attack. Experimental results on public databases and security analysis show the validity of the proposed cancelable template. <s> BIB013 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> Fingerprint and finger-vein based cancelable multi-biometric template design.Flexible feature-level fusion strategy with three fusion options.Enhanced partial discrete Fourier transform based non-invertible transformation.High-performing cancelable multi-biometric templates with strong security. Compared to uni-biometric systems, multi-biometric systems, which fuse multiple biometric features, can improve recognition accuracy and security. However, due to the challenging issues such as feature fusion and biometric template security, there is little research on cancelable multi-biometric systems. In this paper, we propose a fingerprint and finger-vein based cancelable multi-biometric system, which provides template protection and revocability. The proposed multi-biometric system combines the minutia-based fingerprint feature set and image-based finger-vein feature set. We develop a feature-level fusion strategy with three fusion options. Matching performance and security strength using these different fusion options are thoroughly evaluated and analyzed. Moreover, compared with the original partial discrete Fourier transform (P-DFT), security of the proposed multi-biometric system is strengthened, thanks to the enhanced partial discrete Fourier transform (EP-DFT) based non-invertible transformation. <s> BIB014 </s> Security and Accuracy of Fingerprint-Based Biometrics: A Review <s> Cancelable Biometrics <s> In spite of the benefits of biometric-based authentication systems, there are few concerns raised because of the sensitivity of biometric data to outliers, low performance caused due to intra-class variations, and privacy invasion caused by information leakage. To address these issues, we propose a hybrid fusion framework where only the protected modalities are combined to fulfill the requirement of secrecy and performance improvement. This paper presents a method to integrate cancelable modalities utilizing Mean-Closure Weighting (MCW) score level and Dempster-Shafer (DS) theory based decision level fusion for iris and fingerprint to mitigate the limitations in the individual score or decision fusion mechanisms. The proposed hybrid fusion scheme incorporates the similarity scores from different matchers corresponding to each protected modality. The individual scores obtained from different matchers for each modality are combined using MCW score fusion method. The MCW technique achieves the optimal weight for each matcher involved in the score computation. Further, DS theory is applied to the induced scores to output the final decision. The rigorous experimental evaluations on three virtual databases indicate that the proposed hybrid fusion framework outperforms over the component level or individual fusion methods (score level and decision level fusion). As a result, we achieve (48%, 66%), (72%, 86%) and (49%, 38%) of performance improvement over unimodal cancelable iris and unimodal cancelable fingerprint verification systems for Virtual_A, Virtual_B, and Virtual_C databases, respectively. Also, the proposed method is robust enough to the variability of scores and outliers satisfying the requirement of secure authentication. <s> BIB015
The concept of cancelable biometrics is that the original template data is transformed into a different version by using a non-invertible transformation function in the enrollment stage. Query data in the verification stage are applied the same non-invertible transformation. Matching is conducted in the transformed domain using the transformed template and query data BIB001 . Ratha et al. BIB002 initiated three different transformation functions, known as Cartesian, polar, and functional transformations. The proposed transformation functions intentionally distort the original features, so that it is infeasible or computationally difficult to retrieve raw template data. However, one drawback is that the proposed method is registration-based, and hence, accurate detection of singular points is required. Usually, accurate registration is hard because of biometric uncertainty (e.g., image displacement, non-linear distortion, and acquisition condition). Jin et al.  proposed a two factor authentication method called bio-hashing. Bio-hashing combines token-based data with fingerprint features by the iterative inner product to create a new feature set. Then each value in the feature set is converted to a binary number based on a predefined threshold. Lee et al. BIB003 generated cancelable fingerprint templates by extracting a rotation-and translation-invariant feature for each minutiae, which is deemed to be the first alignment-free cancelable fingerprint template design. Ahn et al. BIB004 used triplets of minutiae as a feature set, and transformation is performed on geometrical properties derived from the triplets. Yang et al. BIB005  templates by using both local and global features. Local features include distances and relative angles between minutiae pairs, while global features include orientation and ridge frequency. In this research, the distance of a pair of minutiae is transformed using a perpendicular projection, so as to derive the non-invertible transformation. Ahmad and Hu BIB006 proposed an alignment-free structure based on a pair-polar coordinate. In this structure, the relative position of each minutia to all other minutiae among a polar coordinate range is utilized. From any two minutiae, three local features are extracted and transformed by a functional transformation to generate the cancelable template. Based on the minutia structure in BIB006 , Wang et al. BIB010    further improved system security and accuracy by proposing some new transformation functions, such as infinite-to-one mapping, curtailed circular convolution, and partial Hadamard transform. Zhang et al. BIB008 designed a combo plate and a functional transformation to produce cancelable templates based on the Minutia Cylinder-Code (MCC) BIB007 . MCC is a well-known local minutia descriptor, which is based on 3D local structures associated with each minutia. The authors of the MCC later proposed a template protection method named P-MCC  , which performs a KL transformation on the MCC feature representation. However, P-MCC does not have the property of revocability. Then, 2P-MCC was proposed to add cancelability to P-MCC using a partial permutation based scheme BIB009 . Later, Arjona et al. BIB012 presented a secure fingerprint matching approach, named P-MCC-PUFs, which contains two factors based on P-MCC and PUFs (Physically Unclonable Functions). The proposed scheme achieves the best performance when the length of the feature vector is set to 1024 bits and provides strong data privacy and security. Yang et al. BIB013 designed a cancelable fingerprint template based on random projection. The designed template can defend attacks via record multiplicity (ARM) owing to the feature decorrelation algorithm. In the meantime, a Delaunay triangulation-based local structure proposed in the scheme can reduce the negative effect of nonlinear distortion on matching performance. Sandhya and Prasad BIB011 fused two structures, local structure and distant structure, at the feature level to generate binary-valued features, which are then protected by a random projection based cancelable protection method. To further enhance security and recognition performance, some researchers proposed use of multimodal cancelable biometrics. For example, Yang et al. BIB014 proposed a multimodal cancelable biometric system that fuses fingerprint features and finger-vein features to achieve better recognition accuracy and higher security. In the proposed system, an enhanced partial discrete Fourier transform is utilized to provide non-invertibility and revocability. Also, Dwivedi and Dey BIB015 proposed a hybrid fusion (score level and decision level fusion) scheme to integrate cancelable fingerprint and iris modalities to reduce limitations in each individual modality. Experimental results of multimodal cancelable biometric systems exhibit performance improvement over their unimodal counterpart. In this section, the evolution of cancelable biometrics, from the introduction of the idea of cancelable biometrics and some early transformation function designs BIB002 , to the recent multiple cancelable biometrics BIB014 , is presented. There are two categories in the design of cancelable biometrics. One category centers around the extraction and representation of stable biometric features BIB004 BIB005 BIB006 BIB013 so as to achieve better recognition accuracy, and the other category focuses on designing secure transformation functions, which are expected to be mathematically non-invertible BIB010    BIB009 . It is anticipated that future research work in cancelable biometrics will attempt to achieve both better recognition accuracy and stronger security by using multiple cancelable biometrics.