This tutorial paper reviews the theory and design of codes for hiding or embedding information in signals such as images, video, audio, graphics, and text. Such codes have also been called watermarking codes; they can be used in a variety of applications, including copyright protection for digital media, content authentication, media forensics, data binding, and covert communications. Some of these applications imply the presence of an adversary attempting to disrupt the transmission of information to the receiver; other applications involve a noisy, generally unknown, communication channel. Our focus is on the mathematical models, fundamental principles, and code design techniques that are applicable to data hiding. The approach draws from basic concepts in information theory, coding theory, game theory, and signal processing, and is illustrated with applications to the problem of hiding data in images. Keywords—Coding theory, data hiding, game theory, image processing, information theory, security, signal processing, watermarking. I.

The use of digital video offers immense opportunities for creators; however, the ability for anyone to make perfect copies and the ease by which those copies can be distributed also facilitate misuse, illegal copying and distribution (“piracy”), plagiarism, and misappropriation. Popular Internet software based on a peer-to-peer architecture has been used to share copyrighted movies, music, software, and other materials. Concerned about the consequences of illegal copying and distribution on a massive scale, content owners are interested in digital rights management (DRM) systems which can protect their rights and preserve the economic value of digital video. A DRM system protects and enforces the rights associated with the use of digital content. Unfortunately, the technical challenges for securing digital content are formidable and previous approaches have not succeeded. We overview the concepts and approaches for video DRM and describe methods for providing security, including the roles of encryption and video watermarking. Current efforts and issues are described in encryption, watermarking, and key management. Lastly, we identify challenges and directions for further investigation in video DRM.

We consider the problem of detecting hiding in the least significant bit (LSB) of images. Since the hiding rate is not known, this is a composite hypothesis testing problem. We show that under a mild condition on the host probability mass function (PMF), the optimal composite hypothesis testing problem is solved by a related optimal simple hypothesis testing problem. We then develop practical tests based on the optimal test and exhibit their superiority over Stegdetect, a popular steganalysis method used in practice.

Abstract — By abandoning the assumption of an infinite document to watermark ratio, we recompute the achievable rates for Eggers’s Scalar Costa Scheme (SCS, also known as Scalar Distortion Compensated Dither Modulation) and show, as opposed to the results reported by Eggers, that the achievable rates of SCS are always larger than those of spread spectrum (SS). Moreover, we show that for small Watermark to Noise Ratios, SCS becomes equivalent to a two-centroid problem, thus revealing interesting relations with SS and with Malvar’s Improved Spread Spectrum (ISS). We also show an interesting behavior for the optimal distortion compensation parameter. All these results aim at filling an existing gap in watermarking theory and have important consequences for the design of efficient decoders for data hiding problems. I.

Abstract not found

In this paper a novel theoretical security analysis will be presented for data hiding methods with side-information, based on Costa's dirty paper scheme. We quantify the information about the secret key that leaks from the observation of watermarked signals, using the mutual information as analytic tool for providing a fair comparison between the original Costa's scheme, Distortion Compensated - Dither Modulation and Spread Spectrum.

The main goal of this study consists in the development of the worst case additive attack (WCAA) for quantization-based methods using as design criteria the bit error rate probability and the maximum achievable rate of reliable communications. Our analysis is focused on the practical scheme known as a distortion compensation dither modulation (DC-DM). From the mathematical point of view, the problem of the worst case attack (WCA) design using probability of error as a cost function can be formulated as the maximization of the average probability of error subject to the introduced distortion for a given decoding rule. When mutual information is selected as a cost function, a solution of the minimization problem should provide such an attacking noise probability density function (pdf) that will maximally decrease the rate of reliable communications for an arbitrary decoder structure. The results show that within the class of additive noise attacks the developed attack leads to a stronger performance decrease for the considered class of embedding techniques than the AWGN or the uniform noise attacks.

Abstract—Security of quantization index modulation (QIM) watermarking methods is usually sought through a pseudorandom dither signal which randomizes the codebook. This dither plays the role of the secret key (i.e., a parameter only shared by the watermarking embedder and decoder), which prevents unauthorized embedding and/or decoding. However, if the same dither signal is reused, the observation of several watermarked signals can provide sufficient information for an attacker to estimate the dither signal. This paper focuses on the cases when the embedded messages are either known or constant. In the first part of this paper, a theoretical security analysis of QIM data hiding measures the information leakage about the secret dither as the mutual information between the dither and the watermarked signals. In the second part, we show how set-membership estimation techniques successfully provide accurate estimates of the dither from observed watermarked signals. The conclusion of this twofold study is that current QIM watermarking schemes have a relative low security level against this scenario because a small number of observed watermarked signals yields a sufficiently accurate estimate of the secret dither. The analysis presented in this paper also serves as the basis for more involved scenarios. Index Terms—Equivocation, lattice data hiding, mutual information, quantization index modulation, set-membership estimation, watermarking security. I.

Abstract—This paper focuses on a coding approach for effective analysis and design of secure watermark-based multimedia authentication systems. We provide a design framework for semi-fragile watermark-based authentication such that both objectives of robustness and fragility are effectively controlled and achieved. Robustness and fragility are characterized as two types of authentication errors. The authentication embedding and verification structures of the semi-fragile schemes are derived and implemented using lattice codes to minimize these errors. Based on the specific security requirements of authentication, cryptographic techniques are incorporated to design a secure authentication code structure. Using nested lattice codes, a new approach, called MSB-LSB decomposition, is proposed which we show to be more secure than previous methods. Tradeoffs between authentication distortion and implementation efficiency of the secure authentication code are also investigated. Simulations of semi-fragile authentication methods on real images demonstrate the effectiveness of the MSB-LSB approach in simultaneously achieving security, robustness, and fragility objectives. Index Terms—Digital watermarking, lattice codes, message authentication code, multimedia authentication, semi-fragile authentication. I.

Abstract. This paper presents an extension of the classical Quantization Index Modulation (QIM) data-hiding scheme in the context of valumetric distortions. This scheme uses a fractal quantization structure during the detection but also a content dependent quantization grid to achieve both global constant robustness and the ability to recover the watermark after non-linear valumetric distortions. Previous works are first presented. Then the construction of a floating quantizer that addresses the problem of non-linear transformations is introduced. The embedding and detection schemes for digital image watermarking are afterward introduced, the main characteristic of this scheme is the fact that the detection scheme can use a hierarchical set of quantizers to deal with non-linear valumetric transforms while preserving an average constant quantization step. Finally the performance of this scheme and the comparison with other robust quantization schemes considering valumetric transforms and noise addition are presented. 1