Digital watermarking algorithms based on wavelet transforms provide increased performance and perceptual quality. This thesis proposes two wavelet-based schemes: one robust and one fragile. Robust watermarks should withstand attacks, such as compression, while maintaining the data integrity. The first approach presented is an algorithm which implements image watermarking in the domain of an overcomplete, or redundant, wavelet transform. Alternately, fragile watermarks are intended for use in applications wherein any loss of image quality is not acceptable. In the second approach presented, data embedding in the domain of an integer wavelet transform is considered. An algorithm is proposed that uses a bilevel image coder to compress a chosen bitplane, thereby providing space in which to store a payload while guaranteeing perfect image recovery.

<p><font face="CMR12"> <p align="left">Cryptology is the study of systems that typically originate from a consideration of the ideal circumstances under which secure information exchange is to take place. It involves the study of cryptographic and other processes that might be introduced for breaking the output of such systems - cryptanalysis. This includes the introduction of formal mathematical methods for the design of a cryptosystem and for estimating its theoretical level of security</p> </font></p>

Many digital watermarking schemes have been proposed for copyright protection recently due to the rapid growth of multimedia data distribution. Robustness is one of the crucial important issues in watermarking. But, most of traditional digital watermarking schemes is normally not to resist both geometric distortion and signal processing attacks well. There are two different types of solutions to resisting geometrical attacks: nonblind and blind methods. With the noblind approach, due to availability of the original image, the problem can be resolved with a good solution by elective search between the geometrically attacked and unattacked image. The blind solution, which does not use the original image in watermark extraction, is obviously more challenging. In this research, we propose a blind watermarking scheme which based on histogram property. So that, we propose a novel scheme to define the lattice structure of color space of host image for embedding watermark data. We utilize the histograms of various properties that calculated from the host image, and partition each histogram space into several divisions with dynamic interval. The number of pixels of each division is equal. And then we embed watermark data by modifying distribution of each division. The experimented results present the algorithm is robust to resist common geometric attacks and high quality JPEG compression at the same time.

<p><font face="CMR12"> <p align="left">Cryptology is the study of systems that typically originate from a consideration of the ideal circumstances under which secure information exchange is to take place. It involves the study of cryptographic and other processes that might be introduced for breaking the output of such systems - cryptanalysis. This includes the introduction of formal mathematical methods for the design of a cryptosystem and for estimating its theoretical level of security</p> </font></p>

Philosophiae Doctor - PhD / Cryptology is the study of systems that typically originate from a consideration of the ideal circumstances under which secure information exchange is to take place. It involves the study of cryptographic and other processes that might be introduced for breaking the output of such systems - cryptanalysis. This includes the introduction of formal mathematical methods for the design of a cryptosystem and for estimating its theoretical level of security

M.Ing. / The objective of this research is to develop a new robust and efficient adaptive watermarking method for JPEG compressed images, in which the watermark can survive even if the watermarked image undergoes manipulations. In this thesis, we present two image watermarking methods: one based on the spatial domain and the other on the DCT-based domain. Both approaches, which embed meaningful information into images for copyright protection, are blind watermarking schemes. To illustrate the robustness and performance enhancement derived from Error Correction Codes (ECC) when applied to watermarking, we propose Method I based on the Direct Sequence Spread Spectrum (DSSS) technique in conjunction with Reed-Solomon codes for raw images in the spatial domain. As is evident from our results, the introduction of Reed- Solomon codes improves the robustness of a watermark. Also, employing the properties of pseudo-noise (PN) to deal with cropping attacks is investigated for this method. Based on Method I, we propose Method II that takes into account the properties of JPEG images and exploits the advantages of error correction codes (ECC). Furthermore, some modifications are introduced in the basic Spread Spectrum watermarking to improve the accuracy of the watermark retrieval process. Several experimental results are provided to demonstrate the performance of the proposed schemes. In these experiments, JPEG compression, cropping, brightness/contrast adjustment, median filtering and noise addition are used as watermark attacks to evaluate the robustness. The experimental results show that the proposed scheme (Method II) is very robust against common image processing attacks.

The digital image watermarking is a process that embeds a secrete sequence into a digital image or a video segment to protect its copyright information. There are several methods utilized to deal with the watermarking problem. There are in total two different kinds: the popular neural network and the traditional methods. And for the traditional methods, according to their working region, they can be divided into two groups: spatial domain-related algorithms (e.g., LSB SVD) and transformed domain algorithms (e.g., DCT, DWT). The spatial domain algorithms are the methods that directly work on the pixel values of the image, while the transformed domain algorithms are the methods that work on the rate of change of the image pixels. In the thesis, first of all, we are going to propose a modified hybrid the scheme, which has better results compared with the paper (Lin and Wan 2016). Then, we are going to offer a brand-new method concerning the LDPC-LDGM coding structure in the area of information theory to deal with the digital watermarking problem. Notice that this LDGM-LDPC nested code watermarking scheme only provides a particular case example, which is implemented by one of the teammates Dr. Mahdi, and there is still much space for improvement. However, according to the step tests in chapter 4.4, we have achieved a reasonably good result in imperceptibility and robustness. / Thesis / Master of Applied Science (MASc)

Reversible watermarking techniques extract the watermark and recover the original image from the watermarked image without any distortion. They have been applied for those sensitive fields, such as the medicine and the military. In this thesis, a novel watermarking algorithm using multi-prediction values has been proposed. It exploits the correlation between the original pixel and the neighboring pixels to obtain twelve prediction candidates, and then selects a candidate as the prediction value according to the original pixel and the temporary prediction value. Due to the algorithm use the original pixel as one of the parameters to decide the prediction value, our prediction values are obtained with great precision. The experimental results reveal that the performance of our proposed method outperforms that proposed by Sachnev. For example the variance of the prediction errors histogram obtained by the proposed method is less than that obtained by the algorithm proposed by Sachnev et al. about 44.2%; the mean PSNR greater than about 1.47 dB and 1.1 dB under the watermark capacity 0~0.04 bpp and 0.04~0.5 bpp, respectively. Therefore, the proposed method is especially appropriate for embedding watermark in low or medium capacity. Keyword¡G reversible watermarking, watermarking, prediction, histogram shifting.

When video transmits over error-prone channels, the fragile property of compressed stream makes it sensitive to bit error. Often even a slight error can make video unable to correctly decode. Therefore, there is a need for a good error control method to solve the problem. This paper presents a novel error detection and concealment strategy along with watermark technique. The proposed watermark-based scheme utilizes two kinds of watermark technique, a fragile watermark is used to detect and localize errors, and a robust watermark is used to reconstruct error areas when errors exist. Experimental results show the proposed watermark-based scheme has good error detection capabilities and complete error recovery information, therefore significant improves video quality after errors happened, especially in the case of higher loss probabilities.

Modern technologies have eased the way for adversaries to bypass the conventional identity authentication and identification processes; hence security systems have been developed to a great extent for protection of privacy and security of identities in different applications. The focus of this thesis is digital watermarking, security and privacy, as well as the ability to employ electrocardiogram as a method to enhance the security and privacy level. A high capacity reversible multiple watermarking scheme is introduced to mainly target the medical images. Furthermore, the use of ECG biometric signals in the form of the embedded watermark is studied. Experimental results indicate that the reversible data hiding scheme outperforms other approaches in the literature in terms of payload capacity and marked image quality. Results from the ECG mark embedding also show that no major degradation in performance is noticeable compared to the case where no watermarking is needed.