Orientador: Alexandre César Rodrigues da Silva / Resumo: Com a crescente evolução dos equipamentos eletrônicos, muitos dados digitais têm sido produzidos, copiados e distribuídos com facilidade, gerando uma grande preocupação com a sua segurança. Dentre as várias técnicas usadas para proteger os dados digitais, tem-se as técnicas de inserção e extração de marca d'água em imagens digitais. Uma marca d'água pode ser qualquer informação como, por exemplo, um código, um logotipo, ou uma sequência aleatória de letras e números, que vise garantir a autenticidade e a proteção dos direitos autoriais dos dados. Neste trabalho, estudou-se sobre as técnicas existentes de inserção e extração de marca d'água digital, abordando desde seu conceito até o desenvolvimento de algoritmos de inserção e extração de marca d'água em imagens digitais. Desenvolveu-se um método para aumentar a robustez de técnicas de marca d' água digital pela decomposição da imagem em duas partes: estrutural (áreas homogêneas) e de detalhes (áreas com ruídos, texturas e bordas). Contudo, a marca d'água é inserida na parte de detalhes por se tratar de áreas menos afetadas por operações de processamento digital de imagens. Os resultados mostraram que o método proposto aumentou a robustez das técnicas da marca d'água testadas. Baseado nos resultados obtidos, desenvolveu-se uma nova técnica de marca d'água digital, utilizando a transformada discreta de wavelets, a decomposição de imagens e a transformada discreta do cosseno. / Abstract: With the increasing evolution of technological equipment, many digital data have been easily produced, copied and distributed by generating a great concern for their security. Among the various techniques used to protect the digital data, there are techniques for inserting and extracting a watermark into digital images. A watermark can be any information, such as a code, a logo, or a random sequence of letters and numbers, aiming to ensure the authenticity and copyright protection. In this work are studied, existing insertion and extraction techniques in digital watermarking, by covering from its concept to the development of watermark insertion and extraction algorithms, in digital images. A method was developed to increase the robustness of digital watermarking techniques by decomposing the image into two parts: structural (homogeneous areas) and details (areas with noises, textures and edges). However, the watermark is inserted in the detail area due to be less affected areas by digital image processing. The results showed that the proposed method increased the robustness of the tested watermarking techniques. Based on the results obtained, we developed a new digital watermark technique using discrete wavelet transform, image decomposition and discrete cosine transform. / Doutor

Submitted by Ivan Oliveira Lopes (io.lopes@ifsp.edu.br) on 2018-09-22T02:34:15Z No. of bitstreams: 1 MARDI_Marca dagua Robusta via Decomposicao de Imagens.pdf: 69551246 bytes, checksum: 895274cb196d7f5075a7bf92bba60e9f (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-09-25T19:59:12Z (GMT) No. of bitstreams: 1 lopes_io_dr_ilha.pdf: 69617454 bytes, checksum: 7a93538756770bc0935aa4b85b95f4b7 (MD5) / Made available in DSpace on 2018-09-25T19:59:12Z (GMT). No. of bitstreams: 1 lopes_io_dr_ilha.pdf: 69617454 bytes, checksum: 7a93538756770bc0935aa4b85b95f4b7 (MD5) Previous issue date: 2018-07-27 / Com a crescente evolução dos equipamentos eletrônicos, muitos dados digitais têm sido produzidos, copiados e distribuídos com facilidade, gerando uma grande preocupação com a sua segurança. Dentre as várias técnicas usadas para proteger os dados digitais, tem-se as técnicas de inserção e extração de marca d'água em imagens digitais. Uma marca d'água pode ser qualquer informação como, por exemplo, um código, um logotipo, ou uma sequência aleatória de letras e números, que vise garantir a autenticidade e a proteção dos direitos autoriais dos dados. Neste trabalho, estudou-se sobre as técnicas existentes de inserção e extração de marca d'água digital, abordando desde seu conceito até o desenvolvimento de algoritmos de inserção e extração de marca d'água em imagens digitais. Desenvolveu-se um método para aumentar a robustez de técnicas de marca d' água digital pela decomposição da imagem em duas partes: estrutural (áreas homogêneas) e de detalhes (áreas com ruídos, texturas e bordas). Contudo, a marca d'água é inserida na parte de detalhes por se tratar de áreas menos afetadas por operações de processamento digital de imagens. Os resultados mostraram que o método proposto aumentou a robustez das técnicas da marca d'água testadas. Baseado nos resultados obtidos, desenvolveu-se uma nova técnica de marca d'água digital, utilizando a transformada discreta de wavelets, a decomposição de imagens e a transformada discreta do cosseno. / With the increasing evolution of technological equipment, many digital data have been easily produced, copied and distributed by generating a great concern for their security. Among the various techniques used to protect the digital data, there are techniques for inserting and extracting a watermark into digital images. A watermark can be any information, such as a code, a logo, or a random sequence of letters and numbers, aiming to ensure the authenticity and copyright protection. In this work are studied, existing insertion and extraction techniques in digital watermarking, by covering from its concept to the development of watermark insertion and extraction algorithms, in digital images. A method was developed to increase the robustness of digital watermarking techniques by decomposing the image into two parts: structural (homogeneous areas) and details (areas with noises, textures and edges). However, the watermark is inserted in the detail area due to be less affected areas by digital image processing. The results showed that the proposed method increased the robustness of the tested watermarking techniques. Based on the results obtained, we developed a new digital watermark technique using discrete wavelet transform, image decomposition and discrete cosine transform.

The aim of this dissertation is to develop a new algorithm to embed a watermark in JPEG compressed images, using encoding methods. This encompasses the embedding of proprietary information, such as identity and authentication bitstrings, into the compressed material. This watermark encoding scheme involves combining entropy coding with homophonic coding, in order to embed a watermark in a JPEG image. Arithmetic coding was used as the entropy encoder for this scheme. It is often desired to obtain a robust digital watermarking method that does not distort the digital image, even if this implies that the image is slightly expanded in size before final compression. In this dissertation an algorithm that combines homophonic and arithmetic coding for JPEG images was developed and implemented in software. A detailed analysis of this algorithm is given and the compression (in number of bits) obtained when using the newly developed algorithm (homophonic and arithmetic coding). This research shows that homophonic coding can be used to embed a watermark in a JPEG image by using the watermark information for the selection of the homophones. The proposed algorithm can thus be viewed as a ‘key-less’ encryption technique, where an external bitstring is used as a ‘key’ and is embedded intrinsically into the message stream. The algorithm has achieved to create JPEG images with minimal distortion, with Peak Signal to Noise Ratios (PSNR) of above 35dB. The resulting increase in the entropy of the file is within the expected 2 bits per symbol. This research endeavor consequently provides a unique watermarking technique for images compressed using the JPEG standard. / Dissertation (MEng)--University of Pretoria, 2008. / Electrical, Electronic and Computer Engineering / unrestricted

This thesis presents a secure digital camera (SDC) that inserts biometric data into images found in forms of identification such as the newly proposed electronic passport. However, putting biometric data in passports makes the data vulnerable for theft, causing privacy related issues. An effective solution to combating unauthorized access such as skimming (obtaining data from the passport's owner who did not willingly submit the data) or eavesdropping (intercepting information as it moves from the chip to the reader) could be judicious use of watermarking and encryption at the source end of the biometric process in hardware like digital camera or scanners etc. To address such issues, a novel approach and its architecture in the framework of a digital camera, conceptualized as an SDC is presented. The SDC inserts biometric data into passport image with the aid of watermarking and encryption processes. The VLSI (very large scale integration) architecture of the functional units of the SDC such as watermarking and encryption unit is presented. The result of the hardware implementation of Rijndael advanced encryption standard (AES) and a discrete cosine transform (DCT) based visible and invisible watermarking algorithm is presented. The prototype chip can carry out simultaneous encryption and watermarking, which to our knowledge is the first of its kind. The encryption unit has a throughput of 500 Mbit/s and the visible and invisible watermarking unit has a max frequency of 96.31 MHz and 256 MHz respectively.

This Thesis deals with a method to enforce the intellectual property rights and protect digital media from tampering – Digital Audio Watermarking. The main aim of this work is implement an audio watermarking algorithm. The theoretical part defined basic terms, methods and processes, which are used in this area. The practical part shows a process of embedding the digital signature into a host signal and her backward extraction. The embedding rule used spread spectrum technique and a psychoacoustic model. The implemented psychoacoustic model involves two properties of the human auditory system which are frequency masking and representation the frequency scale on limited bands called critical bands. The model is relatively new and based on the DWPT. In terms of above model is then the digital watermark embedded in the wavelet domain. This algorithm is implemented in technical software MATLAB. One part of this work focuses on robustness tests of the algorithm. Common signal processing modifications are applied to the watermarked audio as follows: Cutting of the audio, re-sampling, lossy compression, filtering, equalization, modulation effects, noise addition. The last part of the thesis presents subjective and objective methods usable in order to judge the influence of watermarking embedding on the quality of audio tracks called transparency.

Goals of this work are to summarize the process and existing methods of 3D models watermarking, to choose relevant methods for embedding/extraction of a watermark to/from 3D models. The final solution is based on Spectral Mesh Compression technique. This method is robust, imperceptible and informed. The embedded watermark is detectable and robust against geometrical transformations, added random noise, mesh smoothing and simplification, compression and cropping.  The realized tool allows a user to embedding watermark into the mesh, modify the mesh and extraction of a watermark from mesh. Testing was conducted on a set of 5 models differing in size, shape and density of points. The resulting tool inserts a watermark composed of four characters that can detect both undamaged models and the models affected. Among the attacks against which the watermark is robust, include transformations, rotation, scale, adaptive random noise, and combination of this.

This thesis deals with copyright protection and content authentication for still images. New blind transform domain block based algorithms using one-level and two-level Discrete Wavelet Transform (DWT) were developed for copyright protection. The mobile number with international code is used as the watermarking data. The robust algorithms used the Low-Low frequency coefficients of the DWT to embed the watermarking information. The watermarking information is embedded in the green channel of the RGB colour image and Y channel of the YCbCr images. The watermarking information is scrambled by using a secret key to increase the security of the algorithms. Due to the small size of the watermarking information comparing to the host image size, the embedding process is repeated several times which resulted in increasing the robustness of the algorithms. Shuffling process is implemented during the multi embedding process in order to avoid spatial correlation between the host image and the watermarking information. The effects of using one-level and two-level of DWT on the robustness and image quality have been studied. The Peak Signal to Noise Ratio (PSNR), the Structural Similarity Index Measure (SSIM) and Normalized Correlation Coefficient (NCC) are used to evaluate the fidelity of the images. Several grey and still colour images are used to test the new robust algorithms. The new algorithms offered better results in the robustness against different attacks such as JPEG compression, scaling, salt and pepper noise, Gaussian noise, filters and other image processing compared to DCT based algorithms. The authenticity of the images were assessed by using a fragile watermarking algorithm by using hash function (MD5) as watermarking information embedded in the spatial domain. The new algorithm showed high sensitivity against any tampering on the watermarked images. The combined fragile and robust watermarking caused minimal distortion to the images. The combined scheme achieved both the copyright protection and content authentication.

This dissertation explores the potential of EMD as analyzing tool for audio and speech processing. This signal expansion into IMFs is adaptive and without any prior assumptions (stationarity and linearity) on the signal to be analyzed. Salient properties of EMD such as dyadic filter bank structure, quasi-symmetry of IMF and fully description of IMF by its extrema, are exploited for denoising, coding and watermarking purposes. In speech signals denoising, we initially proposed a technique based on IMFs thresholding. A comparative analysis of performance of this technique compared to the denoising technique based on the wavelet. Then, to remedy the problem of the MMSE filters which requires an estimation of the spectral properties of noise, we introduced the ACWA filter in the denoising procedure. The proposed approach is consisted to filter all IMFs of the noisy signal by ACWA filter. This filtering approach is implemented in the time domain, and also applicable in the context of colored noise. Finally, to handle the case of hybrid speech frames, that is composed of voiced and unvoiced speech, we introduced a stationarity index in the denoising approach to detect the transition between the mixture of voiced and unvoiced sounds. In audio signals coding, we proposed four compression approaches. The first two approaches are based on the EMD, and the other two approaches exploit the EMD in association with Hilbert transform. In particular, we proposed to use a predictive coding of the instantaneous amplitude and frequency of the IMFs Finally, we studied the problem of audio signals watermarking in context of copyright protection. The number of IMFs can be variable depending on the attack type. The proposed approach involves inserting the mark in the extrema of last IMFs. In addition, we introduced a synchronization code in the procedure in order to facility the extraction of the mark. These contributions are illustrated on synthetic and real data and results compared to well established methods such as MMSE filter, wavelets approach, MP3 and AAC coders showing the good performances of EMD based signal processes. These findings demonstrate the real potential of EMD as analyzing tool (in adaptive way) in speech and audio processing.

L’avénement des réseaux sociaux, tel que Facebook, MySpace et LinkedIn, a fourni une plateforme permettant aux individus de rester facilement connectés avec leurs amis, leurs familles ou encore leurs collègues tout en les encourageant activement à partager leurs données personnelles à travers le réseau. Avec la richesse des activités disponibles sur un réseau social, la quantité et la variété des informations personnelles partagées sont considérables. De plus, de part leur nature numérique, ces informations peuvent être facilement copiées, modifiées ou divulguées sans le consentement explicite de leur propriétaire. Ainsi, l’information personnelle révélée par les réseaux sociaux peut affecter de manière concrète la vie de leurs utilisateurs avec des risques pour leur vie privée allant d’un simple embarras à la ruine complète de leur réputation, en passant par l’usurpation d’identité. Malheureusement, la plupart des utilisateurs ne sont pas conscients de ces risques et les outils mis en place par les réseaux sociaux actuels ne sont pas suffisants pour protéger efficacement la vie privée de leurs utilisateurs. En outre, même si un utilisateur peut contrôler l’accès à son propre profil, il ne peut pas contrôler ce que les autres révèlent à son sujet. En effet, les “amis” d’un utilisateur sur un réseau social peuvent parfois révéler plus d’information à son propos que celui-ci ne le souhaiterait. Le respect de la vie privée est un droit fondamental pour chaque individu. Nous pré- sentons dans cette thèse une approche qui vise à accroître la prise de conscience des utilisateurs des risques par rapport à leur vie privée et à maintenir la souveraineté sur leurs données lorsqu’ils utilisent un réseau social. La première contribution de cette thèse réside dans la classification des risques multiples ainsi que les atteintes à la vie privée des utilisateurs d’un réseau social. Nous introduisons ensuite un cadre formel pour le respect de la vie privée dans les réseaux sociaux ainsi que le concept de politique de vie privée (UPP). Celle-ci définie par l’utilisateur offre une manière simple et flexible de spécifier et communiquer leur attentes en terme de respect de la vie privée à d’autres utilisateurs, tiers parties ainsi qu’au fournisseur du réseau social. Par ailleurs, nous dé- finissons une taxonomie (possiblement non-exhaustive) des critères qu’un réseau social peut intégrer dans sa conception pour améliorer le respect de la vie privée. En introduisant le concept de réseau social respectueux de la vie privée (PSNS), nous proposons Privacy Watch, un réseau social respectueux de la vie privée qui combine les concepts de provenance et d’imputabilité afin d’aider les utilisateurs à maintenir la souveraineté sur leurs données personnelles. Finalement, nous décrivons et comparons les différentes propositions de réseaux sociaux respectueux de la vie privée qui ont émergé récemment. Nous classifions aussi ces différentes approches au regard des critères de respect de la vie privée introduits dans cette thèse. / The rise of Social Networking Sites (SNS), such as Facebook, Myspace, and LinkedIn has provided a platform for individuals to easily stay in touch with friends, family and colleagues and actively encourage their users to share personal information. With the wealth of activities available on SNS, the amount and variety of personal information shared is considerable and diverse. Additionally, due to its digital nature, this information can be easily copied, modified and disclosed without the explicit consent of their owner. Personal information disclosed from SNS could affect users’ life, with privacy risks ranging from simple embarrassment to ruining their reputation, or even identity theft. Unfortunately, many users are not fully aware of the danger of divulging their personal information and the current privacy solutions are not flexible and thorough enough to protect user data. Furthermore, even though users of SNS can control access to their own profile, they cannot control what others may reveal about them. Friends can sometimes be untrustworthy and disclose more information about the user than they should. Considering that privacy is a fundamental right for every individual, in this thesis, we present an approach that increases privacy awareness of the users and maintains the sovereignty of their data when using SNS. The first contribution of this thesis is the classification of multiple types of risks as well as user expectations regarding privacy in SNS. Afterwards, we introduce the Privacy Framework for SNS and the concept of User Privacy Policy (UPP) to offer users an easy and flexible way to specify and communicate their privacy concerns to other users, third parties and SNS provider. Additionally, we define a taxonomy (possibly non-exhaustive) of privacy criteria that can enhance the user privacy if they are integrated within the design of a SNS and introduce the concept of a Privacy-enhanced SNS (PSNS). Furthermore, we present also Privacy Watch, a theoretical proposal of a PSNS platform that combines the concept of provenance and accountability to help SNS users maintain sovereignty over their personal data. Finally, we survey and compare several privacy-enhanced SNS that were recently proposed that try to integrate some privacy features directly into the design of the system. We also classify these different approaches with respect to the privacy criteria developed.

Le tatouage invisible d’images d’identité imprimées sur un support en plastique est un problème difficile qui intéresse le monde industriel. Dans cette étude, nous avons développé un algorithme de tatouage robuste aux diverses attaques présentes dans ce cas. Ces attaques sont liées aux processus d’impression/numérisation sur le support plastique ainsi qu’aux dégradations qu’une carte plastique peut rencontrer le long de sa durée de vie. La méthode de tatouage opère dans le domaine de Fourier car cette transformée présente des propriétés d’invariances aux attaques géométriques globales. Une méthode préventive consiste en un prétraitement de l’image originale avant le processus d’insertion qui réduit la variance du vecteur support de la marque. Une méthode corrective comporte deux contre-attaques corrigeant le flou et les variations colorimétriques. Pour une probabilité de fausse alarme de 10⁻⁴, nous avons obtenu une amélioration moyenne de 22% par rapport à la méthode de référence lorsque seule la méthode préventive est utilisée. La combinaison de la méthode préventive avec la méthode corrective correspond à un taux de détection supérieur à 99%. L’algorithme de détection prends moins de 1 seconde pour à une image de 512×512 pixels avec un ordinateur classique ce qui est compatible avec l’application industrielle visée. / Invisible watermarking for ID images printed on plastic card support is a challenging problem that interests the industrial world. In this study, we developed a watermarking algorithm robust to various attacks present in this case. These attacks are mainly related to the print/scan process on the plastic support and the degradations that an ID card can encounter along its lifetime. The watermarking scheme operates in the Fourier domain as this transform has invariance properties against global geometrical transformations. A preventive method consists of pre-processing the host image before the embedding process that reduces the variance of the embeddable vector. A curative method comprises two counterattacks dealing with blurring and color variations. For a false alarm probability of 10⁻⁴, we obtained an average improvement of 22% over the reference method when only preventative method is used. The combination of the preventive and curative methods leads to a detection rate greater than 99%. The detection algorithm takes less than 1 second for a 512×512 image with a conventional computer, which is compatible with the industrial application in question.