Imputation of missing values for compositional data using classical and robust methods

New imputation algorithms for estimating missing values in compositional data are introduced. A first proposal uses the k-nearest neighbor procedure based on the Aitchison distance, a distance measure especially designed for compositional data. It is important to adjust the estimated missing values to the overall size of the compositional parts of the neighbors. As a second proposal an iterative model-based imputation technique is introduced which initially starts from the result of the proposed k-nearest neighbor procedure. The method is based on iterative regressions, thereby accounting for the whole multivariate data information. The regressions have to be performed in a transformed space, and depending on the data quality classical or robust regression techniques can be employed. The proposed methods are tested on a real and on simulated data sets. The results show that the proposed methods outperform standard imputation methods. In the presence of outliers, the model-based method with robust regressions is preferable.     

Two robust remote user authentication protocols using smart cards

With the rapid growth of electronic commerce and enormous demand from variants of Internet based applications, strong privacy protection and robust system security have become essential requirements for an authentication scheme or universal access control mechanism. In order to reduce implementation complexity and achieve computation efficiency, design issues for efficient and secure password based remote user authentication scheme have been extensively investigated by research community in these two decades. Recently, two well-designed password based authentication schemes using smart cards are introduced by Hsiang and Shih (2009) and Wang et al. (2009), respectively. Hsiang et al. proposed a static ID based authentication protocol and Wang et al. presented a dynamic ID based authentication scheme. The authors of both schemes claimed that their protocol delivers important security features and system functionalities, such as mutual authentication, data security, no verification table implementation, freedom on password selection, resistance against ID-theft attack, replay attack and insider attack, as well as computation efficiency. However, these two schemes still have much space for security enhancement. In this paper, we first demonstrate a series of vulnerabilities on these two schemes. Then, two enhanced protocols with corresponding remedies are proposed to eliminate all identified security flaws in both schemes.     

一种块对独立的鲁棒数字图像鉴别方法

随着多媒体数据的广泛使用，其内容的真实性和完整性越来越受到人们的关注，基于内容的多媒体数据鉴别技术成为了一个重要的热点研究领域。根据静态图像的特征，提出了一个用于数字图像的、块对独立的鉴别方法。提取JPEG压缩不变量作为特征，并引入参考块来辅助篡改定位。实验证明，它可以在一定程度上容忍JPEG压缩，对篡改操作敏感，并可以在8^*8像素块的量级上对篡改区域进行精确定位。     

Hiding iris data for authentication of digital images using wavelet theory

This paper introduces an efficient approach to protect the ownership by hiding an iris data into digital image for an authentication purpose. It is based on the theory of wavelets. The idea is to secretly embed biometric data (iris print) in the content of the image identifying the owner. The system is based on an empirical analysis of biometric and watermarking technologies, and it is split into several processes. The first process is based on iris image analysis, which aids the generation of the iris code (watermark); the second and the third processes deal with embedding and detecting a watermark; and the last process deals with the authentication. A new metric that measures the objective quality of the image based on the detected watermark bit is introduced, which does not require the original unmarked image for watermark detection. Simulation results show the effectiveness and efficiency of the proposed approach. The text was submitted by the author in English.     

A robust authentication scheme for telecare medical information systems

Multimedia Tools and Applications - With the speedy progress in technology, the Internet has become a non-separable part of human life. It is obvious to use the Internet in all fields and medical...     

New robust biometrics-based mutual authentication scheme with key agreement using elliptic curve cryptography

In this work, we demonstrate that Chaudhry et al.’s recent biometrics-based three factor authentication scheme is vulnerable to the denial of service attack, and it also fails to provide perfect forward secrecy because it only uses the lightweight symmetric key primitives to ensure security. To enhance the information security, this article presents a new robust biometrics-based mutual authentication scheme using elliptic curve cryptography for client-server architecture based applications in mobile environment. The proposed scheme supports session key agreement and flawless mutual authentication of participants, which is proved under the BAN logic. Moreover, the proposed scheme provides prefect security attributes and resists all known attacks, and it has perfect performance in communication cost. Thereby, the proposed scheme is more suitable for client-server architecture based applications.     

一种WSNs中的强实体认证协议

无线传感器网络(WSNs)由于其部署环境的开放性、资源的有限性等特点,比传统网络更易受到安全方面的威胁,其安全问题变得极为重要。针对WSNs中的认证机制的效率和安全问题,提出了一种有效的强实体认证协议。通过采用秘密共享方案,通过多个节点对用户进行认证,能够有效地防止非法用户加入网络。通过实验分析和对比表明:协议既能满足网络对安全的需求,又能最大程度地节约传感器节点的能量。     

Reversible DNA data hiding using multiple difference expansions for DNA authentication and storage

Multimedia Tools and Applications - Recently the data hiding techniques on DNA sequence have attracted interest for DNA authentication and high-capacity DNA storage. However, since DNA sequence...     

Video-to-video face authentication system robust to pose variations

High-quality still-to-still (image-to-image) face authentication has shown success under controlled conditions in many safety applications. However, video-to-video face authentication is still challenging due to appearance variations caused by pose changes. In this paper, we propose a video-to-video face authentication system that is robust to pose variations by making use of synthesized frontal face appearance that contains both texture and shape information. To obtain the appearance, we first reconstruct 3D face shape from face feature points detected from the video using active shape model (ASM). Conventional ASM algorithms cannot handle large pose variations and fast head movement exhibited in video sequences. To address these problems, we present a novel prediction-assisted approach that is capable of providing an accurate shape initiation as well as automatically switching on multi-view models for ASM. Then we can generate frontal shape mesh from the reconstructed 3D face shape. Based on the mesh, we synthesize frontal face appearance with the ASM-detected faces in video. For authentication, in order to match the synthesized appearances of enrollment and probe, we propose a 2-directional 2-dimensional client specific fisher’s linear discriminant algorithm. The proposed algorithm is a variant of fisher’s linear discriminant (FLD) and directly computes eigenvectors of image scatter matrices in row and column direction without matrix-to-vector conversion. In experiments, our authentication system is compared with the other state-of-art approaches on public face database and our face database. The results show that our system demonstrates a higher authentication accuracy and pose-robust performance.     

Iterative stepwise regression imputation using standard and robust methods

Imputation of missing values is one of the major tasks for data pre-processing in many areas. Whenever imputation of data from official statistics comes into mind, several (additional) challenges almost always arise, like large data sets, data sets consisting of a mixture of different variable types, or data outliers. The aim is to propose an automatic algorithm called IRMI for iterative model-based imputation using robust methods, encountering for the mentioned challenges, and to provide a software tool in R. This algorithm is compared to the algorithm IVEWARE, which is the “recommended software” for imputations in international and national statistical institutions. Using artificial data and real data sets from official statistics and other fields, the advantages of IRMI over IVEWARE-especially with respect to robustness-are demonstrated.     

基于手机加速度传感器的静态手势身份认证方法

针对智能手机上现有传统身份认证方法的缺点,提出一种基于人体生理震颤的静态手势身份认证方法。该方法在用户按特定静态姿势手持智能手机时,由手机内置的加速度传感器记录因持手机而产生的上肢肌肉震颤,经过信号预处理,得到信号的功率谱密度（ PSD）作为身份模板。通过动态时间规整（ DTW）算法计算待认证信号的PSD和模板之间的相似度,得到认证结果。实验结果表明：该方法的等错误率（ EER）和半错误率（ HTER）均在8%以下,验证了本方法的有效性。     

On the design of data hiding methods robust to lossy compression

The problem of efficient data hiding robust to lossy compression is divided into two subproblems. First is to maximize the resource-which is the permitted distortion of images. The second is the efficient use of the resource by means of sophisticated signaling techniques . We conclude that a good solution to the first problem is choosing magnitude discrete Fourier transform as the domain in which the message signal is embedded. For the signaling method we use a sophisticated signaling technique, using periodic functions to tile the space with signal constellations.     

A 3D face and hand biometric system for robust user-friendly authentication

A complete authentication system based on fusion of 3D face and hand biometrics is presented and evaluated in this paper. The system relies on a low cost real-time sensor, which can simultaneously acquire a pair of depth and color images of the scene. By combining 2D and 3D facial and hand geometry features, we are able to provide highly reliable user authentication robust to appearance and environmental variations. The design of the proposed system addresses two basic requirements of biometric technologies: dependable performance under real-world conditions along with user convenience. Experimental evaluation on an extensive database recorded in a real working environment demonstrates the superiority of the proposed multimodal scheme against unimodal classifiers in the presence of numerous appearance and environmental variations, thus making the proposed system an ideal solution for a wide range of real-world applications, from high-security to personalization of services and attendance control.     

A secure and robust digital signature scheme for JPEG2000 image authentication

In this paper, we present a secure and robust content-based digital signature scheme for verifying the authenticity of JPEG2000 images quantitatively, in terms of a unique concept named lowest authenticable bit rates (LABR). Given a LABR, the authenticity of the watermarked JPEG2000 image will be protected as long as its final transcoded bit rate is not less than the LABR. The whole scheme, which is extended from the crypto data-based digital signature scheme, mainly comprises signature generation/verification, error correction coding (ECC) and watermark embedding/extracting. The invariant features, which are generated from fractionalized bit planes during the procedure of embedded block coding with optimized truncation in JPEG2000, are coded and signed by the sender's private key to generate one crypto signature (hundreds of bits only) per image, regardless of the image size. ECC is employed to tame the perturbations of extracted features caused by processes such as transcoding. Watermarking only serves to store the check information of ECC. The proposed solution can be efficiently incorporated into the JPEG2000 codec (Part 1) and is also compatible with Public Key Infrastructure. After detailing the proposed solution, system performance on security as well as robustness will be evaluated.     

Multimedia image data processing on smartphone for authentication

Multimedia Tools and Applications - The spread of smartphones is rapidly increasing. Such smartphones mainly handle image and video data. In particular, there are many security problems that may...     

用于云计算数据访问的多阶段身份认证

为有效解决云计算数据访问服务的隐私性和安全性问题,提出一种基于多阶段身份认证的云计算隐私保护数据访问算法.在注册阶段基于抑制方法将用户的个人信息存贮在云服务器中,在认证阶段采用口令、一次性令牌和条件属性来高效验证客户端的身份,在数据访问阶段使用数据加密/解密以便在云端实现更高的数据安全级别.将仿真结果与其它算法进行比较,验证了所提算法在隐私保护率、计算复杂度和身份认证精度方面均优于其它方法.     

Improving authentication accuracy using artificial rhythms and cues for keystroke dynamics-based authentication

Keystroke dynamics-based authentication (KDA) is to verify a user’s identity using not only the password but also keystroke dynamics. With a small number of patterns available, data quality is of great importance in KDA applications. Recently, the authors have proposed to employ artificial rhythms and tempo cues to improve data quality: consistency and uniqueness of typing patterns. This paper examines whether improvement in uniqueness and consistency translates into improvement in authentication performance in real-world applications. In particular, we build various novelty detectors using typing patterns based on various strategies in which artificial rhythms and/or tempo cues are implemented. We show that artificial rhythms and tempo cues improve authentication accuracies and that they can be applicable in practical authentication systems.     

Face authentication for multiple subjects using eigenflow

In this paper, we present a novel scheme for face authentication. To deal with variations, such as facial expressions and registration errors, with which traditional intensity-based methods do not perform well, we propose the eigenflow approach. In this approach, the optical flow and the optical flow residue between a test image and an image in the training set are first computed. The optical flow is then fitted to a model that is pre-trained by applying principal component analysis to optical flows resulting from facial expressions and registration errors for the subject. The eigenflow residue, optimally combined with the optical flow residue using linear discriminant analysis, determines the authenticity of the test image. An individual modeling method and a common modeling method are described. We also present a method to optimally choose the threshold for each subject for a multiple-subject authentication system. Experimental results show that the proposed scheme outperforms the traditional methods in the presence of facial expression variations and registration errors.     

The design of controllers for the multivariable robust servomechanism problem using parameter optimization methods

The problem of designing realistic multivariable controllers to solve the servomechanism problem is considered in this paper. Specifically, it is desired to find a controller for a plant to solve the robust servomechanism problem, so that closed-loop stability and asymptotic regulation occur, and also so that other desirable properties of the controlled system, such as fast response, low-interaction, integrity, tolerance to plant variations, etc., occur. The method of design is based on using state space methods via a two-stage process: 1) using theory, determine the existence of a solution and control structure required to solve the problem, and 2) using nonlinear programming methods, determine the unknown controller parameters so as to minimize a performance index for the system subject to certain constraint requirements. Numerous examples, varying from a single-input/single-output to a four-input/four-output system, are given to illustrate the design method, and the results obtained are compared with the results obtained by using other alternate design methods. In all cases, the controllers obtained have been highly competitive with controllers obtained by alternate design methods.     

A robust multimedia authentication and restoration scheme in digital photography

Image authentication and restoration is an important area of modern research. In digital photography, copyright protection is very crucial. Visible signatures distract from the meaning of the photograph as well as they are easy to be removed by using advanced softwares. Invisible watermarks provide protection, offer a better look to photographs than visible watermarking, and prevent the photographs from unauthorized manipulations. A robust multiple watermarking scheme is required which could invisibly protect the content and also should survive the manipulations for later verification and restoration. In this paper, a robust and imperceptible multimedia authentication and restoration scheme is proposed. The security of Advanced Encryption Standard (AES) is utilized to make an encrypted watermark. The encrypted watermark is then embedded into photographs in the salient regions by proposed Feature-Closest Point Transform (F-CPT) algorithm. The second watermark is generated by wavelet decomposition and embedded in the second and third level wavelet sub-bands of the cover photographs. Several security attacks are performed e.g. noise attack, compression attack, resizing attack, rotation attack, collage attack, and cropping attack on multiple watermarked photographs to examine the system robustness by normalized cross correlation (NCC) for retrieved authentication watermarks. Result of PSNR, MSE, and SSIM show the high imperceptibility of our technique and aesthetic score (AS) shows the aesthetic quality of watermarked photographs (WPs).