Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains viii, 69 p. : ill. Includes abstract. Includes bibliographical references (p. 62-69).

Thesis (M.S.)--University of North Texas, Dec., 2008. / Title from title page display. Includes bibliographical references.

Thesis (M.S.)--University of North Texas, Dec., 2008. / Title from title page display. Includes bibliographical references.

Thesis (Ph. D.)--Georgia State University, 2009. / Title from title page (Digital Archive@GSU, viewed July 20, 2010) Michael Weeks, committee chair; Saeid Belkasim, Robert Harrison, Ephraim McLean, committee members. Includes bibliographical references (p. 145-153).

Thesis (M.S.)--Ohio University, March, 2006. / Title from PDF t.p. Includes bibliographical references (p. 47-48)

Covert channel attacks utilize shared resources to indirectly transmit sensitive information to unauthorized parties. Many current operating systems, such as SELinux, rely on generating labels based on a file's security classification and system-wide security policies and then binding these labels to all such files in the filesystem. Enforcement of security policies in such systems occurs at the time of access to a file or resource. Such mechanisms are flawed, however, in that they do not adequately protect against information laundering by means of covert channels. One recent development, Colored Linux, serves as an extension to SELinux and utilizes watermarking algorithms to "color" the contents of files with their respective security classification in order to enhance resistance to information laundering attacks. In this thesis, a mobile agent-based approach to implementing Colored Linux is proposed to automate the process of detecting and coloring receptive hosts' filesystems and to provide monitoring of the colored filesystem for instances of potential information leakage. Implementation details and execution results are included to illustrate the merits of the proposed approach. An evaluation of the performance of this agent-based system is conducted over a single host as well as a local network of machines and detailed here as well. Finally, third-party analysis of the agent system using formal methods is discussed.

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Approved for public release; distribution is unlimited / Perceptual watermarking is a promising technique towards the goal of producing invisible watermarks. It involves the integration of formal perceptual models in the watermarking process, with the purpose of determining those portions of an image that can better tolerate the distortion imposed by the embedding and ensuring that the watermarking will inflict the least possible degradation on the original image . In a previous study the Discrete Cosine Transform was used, and the watermark embedding was done in a non -uniform manner with criteria based on both the host image and the watermark. The decoder model employed made use of apriori access to unmarked and marked images as well as to the watermark. A fair level of success was achieved in this effort. In our research we refine this scheme by integrating a perceptual model and by proposing a modification to the decoder model that makes possible the successful recovery of the watermark without apriori access to it. The proposed perceptual scheme improves the watermark's transparency while at the same time maintains sufficient robustness to quantization and cropping. The proposed semi-blind variation offers adequate transparency and robustness to quantization, but its performance against cropping is considerably degraded. / Lieutenant, Hellenic Navy

This thesis presents a novel singular-value-based semi-fragile watermarking scheme for image content authentication with tampering localization. The proposed scheme first generates a secured watermark bit sequence by performing a logical "xor" operation on a content-based watermark and content-independent watermark, wherein the content-based watermark is generated by a singular-value-based watermark bit sequence that represents intrinsic algebraic image properties, and the content-independent watermark is generated by a private-key-based random watermark bit sequence. It next embeds the secure watermark in the approximation subband of each non-overlapping 4×4 block using the adaptive quantization method to generate the watermarked image. The image content authentication process starts with regenerating the secured watermark bit sequence following the same process mentioned in the secured watermark bit sequence generation. It then extracts a possibly embedded watermark using the parity of the quantization results from the probe image. Next, the authentication process constructs a binary error map, whose height and width are a quarter of those of the original image, using the absolute difference between the regenerated secured watermark and the extracted watermark. It finally computes two authentication measures (i.e., M1 and M2), with M1 measuring the overall similarity between the regenerated watermark and the extracted watermark, and M2 measuring the overall clustering level of the tampered error pixels. These two authentication measures are further seamlessly integrated in the authentication process to confirm the image content and localize any possible tampered areas. The extensive experimental results show that the proposed scheme outperforms four peer schemes and is capable of identifying intentional tampering, incidental modification, and localizing tampered regions.

Safeguarding creative content in a digital form has become increasingly difficult. It is progressively easier to copy, modify and redistribute digital media, which causes great declines in business profits. For example, the International Federation of the Phonographic Industry estimates that in 2001 the worldwide sales of pirated music CDs were 475 million US dollars. While a large amount of time and money is committed to creating intellectual property, legal means have not proven to be sufficient for the protection of this property. Digital watermarking is a steganographic technique that has been proposed as a possible solution to this problem. A digital watermark hides embedded information about the origin, status, owner and/or destination of the data, often without the knowledge of the viewer or user. This dissertation examines a technique for digital watermarking which utilizes properties of the Discrete Wavelet Transform (DWT). Research has been done in this field, but which wavelet family is superior is not adequately addressed. This dissertation studies the influence of the wavelet family when using a blind, nonvisible watermark in digital media. The digital watermarking algorithm uses a database of multiple images with diverse properties. Various watermarks are embedded. Eight different families of wavelets with dissimilar properties are compared. How effective is each wavelet? To objectively measure the success of the algorithm, the influence of the mother wavelet, the imperceptibility of the embedded watermark and the readability of the extracted watermark, the Peak Signal-to-Noise Ratio and the Image Quality Index for each wavelet family and image are obtained. Two common categories of digital watermarking attacks are removing the watermark and rendering the watermark undetectable. To simulate and examine the effect of attacks on the images, noise is added to the image data. Also, to test the effect of reducing an image in size, each image containing the embedded watermark is compressed. The dissertation asks the questions: “Is the wavelet family chosen to implement the algorithm for a blind, nonvisible watermark in digital images of consequence? If so, which family is superior?” This dissertation conclusively shows that the Haar transform is the best for blind, non-visible digital watermarking.