A digital watermark is a message robustly hidden within another digitized signal such as an image, a piece of music, a video, etc. . The principal applications of this technology are copyright protection and document fingerprinting. The robustness of watermarking algorithms against common geometrical deformations has drawn the attention of many researchers in the last ten years. Such distortions can result from usual processing of the media and/or malicious manipulations. As an example, a major concern for digital cinema industry is the illicit copy of movies with video cameras taking place in movie theaters. In this scenario, severe geometric distortions can jeopardize the retrieval of the watermark message from the illicit copies. The limitations and weaknesses of the previously proposed solutions to fight these distortions are presented. We developed a generalized construction method for periodic pseudo-random patterns. Based on these patterns, we designed a spread spectrum watermarking scheme with enhanced security properties. We investigated the detection probability and the interaction between exhaustive search and informed coding strategies. Finally, a scheme for the detection of a periodic structure and for the inversion of affine distortions was presented. We showed that the choice of the periodic repetition size involves a trade-off between robustness and secrecy. Thereafter, we studied the security flaw caused by the lack of secrecy in pilot-registration approaches. We proposed an innovative hiding scheme to remedy this issue. Our solution involves the extraction of robust local references from the content of the cover signal. Using this content normalized interpretation, we showed how one can design robust secret binary mask and modulate pilot signals in watermarking schemes. The efficiency of the approach is demonstrated on pilots derived from periodic structures. We also addressed the assessment of the degradation introduced by a geometrical distortion. We assume that a global rigid transform does not impair the perceptual value of an image and we propose a new criterion based on a local analysis of the geometrical deformations.

The complexity of automotive software has increased dramatically in recent years. New technological advances as well as increasing market competitiveness create a high cost-pressure environment. This thesis seeks to apply established modular principles to a Simulink Model to increase information hiding to improve the maintainability of controls software. A Hybrid Supervisory Controller (HSC) model, developed as part of the McMaster EcoCAR Competition, is used throughout this thesis. The software design process followed during the HSC model development is detailed, as well as providing an example of the application of the Simulink Module Tool, a Simulink add-on developed by Jaskolka et. al. The HSC System decomposition was restructured based on an analysis of the likely changes to the vehicle software, as well the system secrets contained within the model. This thesis also presents an analysis of the original and modular system decompositions, comparing several common software indicators of information hiding, coupling, cohesion, complexity, and testability. The modular decomposition led to a significant improvement in information hiding, both in system changeability and internal implementation. Likely changes to the system propagate to fewer modules and components within the new decomposition, with hardware data separated from behavioral algorithms, and all modules grouped based on shared secrets. The redistribution of algorithms based on separation of concern also led to improvements in coupling, cohesion, and interface complexity. The resulting software design process and modular system decomposition provides a framework for future EcoCAR students to focus on correct design and implementation of hybrid vehicle software. The benefits provided by the application of the Simulink Module Tool also contributes additional data and supporting evidence to the improvements that can be realized within Simulink Models by introducing the concepts of information hiding and modularity. / Thesis / Master of Applied Science (MASc) / The complexity of automotive software has increased dramatically in recent years. New technological advances as well as increasing market competitiveness create a high cost-pressure environment. As a result, improving the development of automotive software and its maintainability has become an increasingly critical issue to solve. This thesis uses a Hybrid Vehicle Controller Model developed within MATLAB Simulink to investigate the possible improvements that can be made to software modularity. The system decomposition is modified using the Simulink Module Tool, and is analyzed regarding improvements to information hiding, interface complexity, and specifically minimizing change propagation. The modular improvements made to the Simulink Model resulted in significant improvements in system changeability and information hiding, providing a useful framework for future EcoCAR students.

Joint source-channel coding (JSCC) has been acknowledged to have superior performance over separate source-channel coding in terms of coding efficiency, delay and complexity. In the first part of this thesis, we study a hybrid digital-analog (HDA) JSCC system to transmit a memoryless Gaussian source over a memoryless Gaussian channel under bandwidth compression. Information-theoretic upper bounds on the asymptotically optimal mean squared error distortion of the system are obtained. An allocation scheme for distributing the channel input power between the analog and the digital signals is derived for the HDA system with mismatched channel conditions. A low-complexity and low-delay version of the system is next designed and implemented. We then propose an image communication application demonstrating the effectiveness of HDA coding. In the second part of this thesis, we consider problems in information hiding. We begin by considering a single-user joint compression and private watermarking (JCPW) problem. For memoryless Gaussian sources and memoryless Gaussian attacks, an exponential upper bound on the probability of error in decoding the watermark is derived. Numerical examples show that the error exponent is positive over a (large) subset of the entire achievable region derived by Karakos and Papamarcou (2003). We then extend the JCPW problem to a multi-user setting. Two encoders independently embed two secret information messages into two correlated host sources subject to a pair of tolerable distortion levels. The (compressed) outputs are subject to multiple access attacks. The tradeoff between the achievable watermarking rates and the compression rates is studied for discrete memoryless host sources and discrete memoryless multiple access channels. We derive an inner bound and an outer bound with single-letter characterization for the achievable compression and watermarking rate region. We next consider a problem where two correlated sources are separately embedded into a common host source. A single-letter sufficient condition is established under which the sources can be successfully embedded into the host source under multiple access attacks. Finally, we investigate a public two-user information hiding problem under multiple access attacks. Inner and outer bounds for the embedding capacity region are obtained with single-letter characterization. / Thesis (Ph.D, Mathematics & Statistics) -- Queen's University, 2007-09-28 23:11:21.398

Unlike encryption, steganography hides the very existence of secret information rather than hiding its meaning only. Image based steganography is the most common system used since digital images are widely used over the Internet and Web. However, the capacity is mostly limited and restricted by the size of cover images. In addition, there is a tradeoff between both steganographic capacity and stego image quality. Therefore, increasing steganographic capacity and enhancing stego image quality are still challenges, and this is exactly our research main aim. Related to this, we also investigate hiding secret information in communication protocols, namely Simple Object Access Protocol (SOAP) message, rather than in conventional digital files. To get a high steganographic capacity, two novel steganography methods were proposed. The first method was based on using 16x16 non-overlapping blocks and quantisation table for Joint Photographic Experts Group (JPEG) compression instead of 8x8. Then, the quality of JPEG stego images was enhanced by using optimised quantisation tables instead of the default tables. The second method, the hybrid method, was based on using optimised quantisation tables and two hiding techniques: JSteg along with our first proposed method. To increase the steganographic capacity, the impact of hiding data within image chrominance was investigated and explained. Since peak signal-to-noise ratio (PSNR) is extensively used as a quality measure of stego images, the reliability of PSNR for stego images was also evaluated in the work described in this thesis. Finally, to eliminate any detectable traces that traditional steganography may leave in stego files, a novel and undetectable steganography method based on SOAP messages was proposed. All methods proposed have been empirically validated as to indicate their utility and value. The results revealed that our methods and suggestions improved the main aspects of image steganography. Nevertheless, PSNR was found not to be a reliable quality evaluation measure to be used with stego image. On the other hand, information hiding in SOAP messages represented a distinctive way for undetectable and secret communication.

Abstract Broadband communication networks and multimedia data available in a digital format opened many challenges and opportunities for innovation. Versatile and simple-to-use software and decreasing prices of digital devices have made it possible for consumers from all around the world to create and exchange multimedia data. Broadband Internet connections and near error-free transmission of data facilitate people to distribute large multimedia files and make identical digital copies of them. A perfect reproduction in digital domain have promoted the protection of intellectual ownership and the prevention of unauthorized tampering of multimedia data to become an important technological and research issue. Digital watermarking has been proposed as a new, alternative method to enforce intellectual property rights and protect digital media from tampering. Digital watermarking is defined as imperceptible, robust and secure communication of data related to the host signal, which includes embedding into and extraction from the host signal. The main challenge in digital audio watermarking and steganography is that if the perceptual transparency parameter is fixed, the design of a watermark system cannot obtain high robustness and a high watermark data rate at the same time. In this thesis, we address three research problems on audio watermarking: First, what is the highest watermark bit rate obtainable, under the perceptual transparency constraint, and how to approach the limit? Second, how can the detection performance of a watermarking system be improved using algorithms based on communications models for that system? Third, how can overall robustness to attacks to a watermark system be increased using attack characterization at the embedding side? An approach that combined theoretical consideration and experimental validation, including digital signal processing, psychoacoustic modeling and communications theory, is used in developing algorithms for audio watermarking and steganography. The main results of this study are the development of novel audio watermarking algorithms, with the state-of-the-art performance and an acceptable increase in computational complexity. The algorithms' performance is validated in the presence of the standard watermarking attacks. The main technical solutions include algorithms for embedding high data rate watermarks into the host audio signal, using channel models derived from communications theory for watermark transmission and the detection and modeling of attacks using attack characterization procedure. The thesis also includes a thorough review of the state-of-the-art literature in the digital audio watermarking.

Stegomalware is the art of hiding malicious software with steganography. Steganography is the technique of hiding data in a seemingly innocuous carrier. The occurrence of stegomalware is increasing, with attackers using ingenious techniques to avoid detection. Through a literature review, this thesis explores prevalent techniques used by attackers and their efficacy. Furthermore, it investigates detection techniques and defensive measures against stegomalware. The results show that embedding information in images is common for exfiltrating data or sending smaller files to an infected host. Word, Excel, and PDF documents are common with phishing emails as the entry vector for attacks. Most of the common Internet protocols are used to exfiltrate data with HTTP, ICMP and DNS showed to be the most prevalent in recent attacks. Machine learning anomaly-based detection techniques show promising results for detecting unknown malware, however, a combination of several techniques seems preferable. Employee knowledge, Content Threat Removal, and traffic normalization are all effective defenses against stegomalware. The stegomalware landscape shows an increase of attacks utilizing obfuscation techniques, such as steganography, to bypass security and it is most likely to increase in the near future.

Approved for public release, distribution is unlimited / The attack of choice for a professional attacker is system subversion: the insertion of a trap door that allows the attacker to bypass an operating system's protection controls. This attack provides significant capabilities and a low risk of detection. One potential design is a trap door that itself accepts new programming instructions. This allows an attacker to decide the capabilities of the artifice at the time of attack rather than prior to its insertion. Early tiger teams recognized the possibility of this design and compared it to the two-card bootstrap loader used in mainframes, since both exhibit the characteristics of compactness and adaptability. This thesis demonstrates that it is relatively easy to create a bootstrapped trap door. The demonstrated artifice consists of 6 lines of C code that, when inserted into the Windows XP operating system, accept additional arbitrary code from the attacker, allowing subversion in any manner the attacker chooses. The threat from subversion is both extremely potent and eminently feasible. Popular risk mitigation strategies that rely on defense-in-depth are ineffective against subversion. This thesis focuses on how the use of the principles of layering, modularity, and information hiding can contribute to high-assurance development methodologies by increasing system comprehensibility. / Civilian, Naval Postgraduate School

Covert communication refers to the process of communicating data through a channel that is neither designed, nor intended to transfer information. Traditionally, covert channels are considered as security threats in computer systems and a great deal of attention has been given to countermeasures for covert communication schemes. The evolution of computer networks led the communication community to revisit the concept of covert communication not only as a security threat but also as an alternative way of providing security and privacy to communication networks. In fact, the heterogeneous structure of computer networks and the diversity of communication protocols provide an appealing setting for covert channels. This dissertation is an exploration on a novel design methodology for undetectable and robust covert channels in communication networks. Our new design methodology is based on the concept of behavioral mimicry in computer systems. The objective is to design a covert transmitter that has enough degrees of freedom to behave like an ordinary transmitter and react normally to unpredictable network events, yet it has the ability to modulate a covert message over its behavioral fingerprints in the network. To this end, we argue that the inherent randomness in communication protocols and network environments is the key in finding the proper medium for network covert channels. We present a few examples on how random behaviors in communication protocols lead to discovery of suitable shared resources for covert channels. The proposed design methodology is tested on two new covert communication schemes, one is designed for wireless networks and the other one is optimized for public communication networks (e.g., Internet). Each design is accompanied by a comprehensive analysis from undetectability, achievable covert rate and reliability perspectives. In particular, we introduced turbo covert channels, a family of extremely robust model-based timing covert channels that achieve provable polynomial undetectability in public communication networks. This means that the covert channel is undetectable against any polynomial-time statistical test that analyzes samples of the covert traffic and the legitimate traffic of the network. Target applications for the proposed covert communication schemes are discussed including detailed practical scenarios in which the proposed channels can be implemented.

Covert communication refers to the process of communicating data through a channel that is neither designed, nor intended to transfer information. Traditionally, covert channels are considered as security threats in computer systems and a great deal of attention has been given to countermeasures for covert communication schemes. The evolution of computer networks led the communication community to revisit the concept of covert communication not only as a security threat but also as an alternative way of providing security and privacy to communication networks. In fact, the heterogeneous structure of computer networks and the diversity of communication protocols provide an appealing setting for covert channels. This dissertation is an exploration on a novel design methodology for undetectable and robust covert channels in communication networks. Our new design methodology is based on the concept of behavioral mimicry in computer systems. The objective is to design a covert transmitter that has enough degrees of freedom to behave like an ordinary transmitter and react normally to unpredictable network events, yet it has the ability to modulate a covert message over its behavioral fingerprints in the network. To this end, we argue that the inherent randomness in communication protocols and network environments is the key in finding the proper medium for network covert channels. We present a few examples on how random behaviors in communication protocols lead to discovery of suitable shared resources for covert channels. The proposed design methodology is tested on two new covert communication schemes, one is designed for wireless networks and the other one is optimized for public communication networks (e.g., Internet). Each design is accompanied by a comprehensive analysis from undetectability, achievable covert rate and reliability perspectives. In particular, we introduced turbo covert channels, a family of extremely robust model-based timing covert channels that achieve provable polynomial undetectability in public communication networks. This means that the covert channel is undetectable against any polynomial-time statistical test that analyzes samples of the covert traffic and the legitimate traffic of the network. Target applications for the proposed covert communication schemes are discussed including detailed practical scenarios in which the proposed channels can be implemented.

For a long time, information hiding has focused on carriers like images and audio files. A problem with these carriers is that they do not support hiding in new types of network-based services. Nowadays, these services often arise as a consequence of the increasingly demand for higher connection speed to the Internet. By introducing streaming media as a carrier of hidden information, hiding in new network-based services is supported. The main purposes with this thesis are to investigate how information can be hidden in streaming media and how it measures up compared to images and audio files. In order to evaluate the approach, we have developed a prototype and used it as a proof of concept. This prototype hides information in some of the TCP/IP header fields and is used to collect experimental data as well. As reference, measurements have been collected from other available carriers of hidden information. In some cases, the results of these experiments show that the TCP/IP header is a good carrier of information. Its performance is outstanding and well suited for hiding information quickly. The tests showed that the capacity is slightly worse though.