Showing papers on "Steganography published in 2004"

Feature-Based steganalysis for JPEG images and its implications for future design of steganographic schemes

Abstract: In this paper, we introduce a new feature-based steganalytic method for JPEG images and use it as a benchmark for comparing JPEG steganographic algorithms and evaluating their embedding mechanisms. The detection method is a linear classifier trained on feature vectors corresponding to cover and stego images. In contrast to previous blind approaches, the features are calculated as an L1 norm of the difference between a specific macroscopic functional calculated from the stego image and the same functional obtained from a decompressed, cropped, and recompressed stego image. The functionals are built from marginal and joint statistics of DCT coefficients. Because the features are calculated directly from DCT coefficients, conclusions can be drawn about the impact of embedding modifications on detectability. Three different steganographic paradigms are tested and compared. Experimental results reveal new facts about current steganographic methods for JPEGs and new de-sign principles for more secure JPEG steganography.

Statistical tools for digital forensics

Abstract: A digitally altered photograph, often leaving no visual clues of having been tampered with, can be indistinguishable from an authentic photograph. As a result, photographs no longer hold the unique stature as a definitive recording of events. We describe several statistical techniques for detecting traces of digital tampering in the absence of any digital watermark or signature. In particular, we quantify statistical correlations that result from specific forms of digital tampering, and devise detection schemes to reveal these correlations.

Cyber warfare: steganography vs. steganalysis

Abstract: For every clever method and tool being developed to hide information in multimedia data, an equal number of clever methods and tools are being developed to detect and reveal its secrets.

An information-theoretic model for steganography

Abstract: An information-theoretic model for steganography with a passive adversary is proposed. The adversary's task of distinguishing between an innocent cover message C and a modified message S containing hidden information is interpreted as a hypothesis testing problem. The security of a steganographic system is quantified in terms of the relative entropy (or discrimination) between the distributions of C and S, which yields bounds on the detection capability of any adversary. It is shown that secure steganographic schemes exist in this model provided the covertext distribution satisfies certain conditions. A universal stegosystem is presented in this model that needs no knowledge of the covertext distribution, except that it is generated from independently repeated experiments.

Feature-based steganalysis for JPEG images and its implications for future design of steganographic schemes

Abstract: In this paper, we introduce a new feature-based steganalytic method for JPEG images and use it as a benchmark for comparing JPEG steganographic algorithms and evaluating their embedding mechanisms. The detection method is a linear classifier trained on feature vectors corresponding to cover and stego images. In contrast to previous blind approaches, the features are calculated as an L 1 norm of the difference between a specific macroscopic functional calculated from the stego image and the same functional obtained from a decompressed, cropped, and recompressed stego image. The functionals are built from marginal and joint statistics of DCT coefficients. Because the features are calculated directly from DCT coefficients, conclusions can be drawn about the impact of embedding modifications on detectability. Three different steganographic paradigms are tested and compared. Experimental results reveal new facts about current steganographic methods for JPEGs and new design principles for more secure JPEG steganography.

Linguistic steganography: survey, analysis, and robustness concerns for hiding information in text

Abstract: Steganography is an ancient art. With the advent of computers, we have vast accessible bodies of data in which to hide information, and increasingly sophisticated techniques with which to analyze and recover that information. While much of the recent research in steganography has been centered on hiding data in images, many of the solutions that work for images are more complicated when applied to natural language text as a cover medium. Many approaches to steganalysis attempt to detect statistical anomalies in cover data which predict the presence of hidden information. Natural language cover texts must not only pass the statistical muster of automatic analysis, but also the minds of human readers. Linguistically naive approaches to the problem use statistical frequency of letter combinations or random dictionary words to encode information. More sophisticated approaches use context-free grammars to generate syntactically correct cover text which mimics the syntax of natural text. None of these uses meaning as a basis for generation, and little attention is paid to the semantic cohesiveness of a whole text as a data point for statistical attack. This paper provides a basic introduction to steganography and steganalysis, with a particular focus on text steganography. Text-based information hiding techniques are discussed, providing motivation for moving toward linguistic steganography and steganalysis. We highlight some of the problems inherent in text steganography as well as issues with existing solutions, and describe linguistic problems with character-based, lexical, and syntactic approaches. Finally, the paper explores how a semantic and rhetorical generation approach suggests solutions for creating more believable cover texts, presenting some current and future issues in analysis and generation. The paper is intended to be both general enough that linguists without training in information security and computer science can understand the material, and specific enough that the linguistic and computational problems are described in adequate detail to justify the conclusions suggested.

Improved detection of LSB steganography in grayscale images

Abstract: We consider methods for answering reliably the question of whether an image contains hidden data; the focus is on grayscale bitmap images and simple LSB steganography. Using a distributed computation network and a library of over 30,000 images we have been carefully evaluating the reliability of various steganalysis methods. The results suggest a number of improvements to the standard techiques, with particular benefits gained by not attempting to estimate the hidden message length. Extensive experimentation shows that the improved methods allow reliable detection of LSB steganography with between 2 and 6 times smaller embedded messages.

Multimedia Security: Steganography and Digital Watermarking Techniques for Protection of Intellectual Property

Abstract: This work explores the myriad of issues regarding multimedia security. It covers various issues, including perceptual fidelity analysis, image, audio, and 3D mesh object watermarking, medical watermarking, and error detection (authentication) and concealment.

On estimation of secret message length in LSB steganography in spatial domain

Abstract: In this paper, we present a new method for estimating the secret message length of bit-streams embedded using the Least Significant Bit embedding (LSB) at random pixel positions. We introduce the concept of a weighted stego image and then formulate the problem of determining the unknown message length as a simple optimization problem. The methodology is further refined to obtain more stable and accurate results for a wide spectrum of natural images. One of the advantages of the new method is its modular structure and a clean mathematical derivation that enables elegant estimator accuracy analysis using statistical image models.

Perturbed quantization steganography with wet paper codes

Abstract: In this paper, we introduce a new approach to passive-warden steganography in which the sender embeds the secret message into a certain subset of the cover object without having to share the selection channel with the recipient. An appropriate information-theoretical model for this communication is writing in memory with (a large number of) defective cells [1]. We describe a simple variable-rate random linear code for this channel (the "wet paper" code) and use it to develop a new steganographic methodology for digital media files - Perturbed Quantization. In Perturbed Quantization, the sender hides data while processing the cover object with an information-reducing operation, such as lossy compression, downsampling, A/D conversion, etc. The sender uses the cover object before processing as side information to confine the embedding changes to those elements of the processed cover object whose values are the most "uncertain". This informed-sender embedding and uninformed-recipient message extraction improves steganographic security because an attacker cannot easily determine from the processed stego object the location of embedding changes. Heuristic is presented and supported by blind steganalysis [2] that a specific case of Perturbed Quantization for JPEG images is significantly less detectable than current JPEG steganographic methods.

Steganography-The Art of Hiding Data

Abstract: Given the shear volume of data stored and transmitted electronically in the world today, it is no surprise that countless methods of protecting such data have evolved. One lesser-known but rapidly growing method is steganography, the art and science of hiding information so that it does not even appear to exist. Moreover, in an ideal world we would all be able to openly send encrypted email or files to each other with no fear of reprisals. However, there are often cases when this is not possible, either because you are working for a company that does not allow encrypted emails or perhaps the local government does not approve of encrypted communication. This is one of the cases where Steganography can help hide the encrypted messages, images, keys, secret data, etc. This paper discusses the purpose of steganography. Explains how steganography is related to cryptography as well as what it can and cannot be used for. It also discusses a brief history of steganography. In addition, some of the tools and software used in steganography are demonstrated and including some discussion of the most popular algorithms involved in these tools. This paper further explains the advantages and disadvantages, as well as, strengths and weaknesses in the use of steganography.

Algorithms for audio watermarking and steganography

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.

Optical and Digital Techniques for Information Security

Abstract: Quantum Cryptography.- New OVDs for Personalized Documents Based on Color Holography and Lippmann Photography.- Distortion- and Noise-Robust Digital Watermarking Using Input and Fourier-Plane Phase Encoding.- Steganography and Encryption Systems Based on Spatial Correlators with Meaningful Output Images.- Optoelectronic Information Encryption with Incoherent Light.- Information Hiding: Steganography and Watermarking.- Watermarking Streaming Video: The Temporal Synchronization Problem.- Secure Display Using Encrypted Digital Holograms.- Compression of Digital Holograms for Secure Three-Dimensional Image Storage and Transmission.- Optical Image Encryption Using Optimized Keys.- Polarization Encoding for an Optical Security System.- Stream Cipher Using Optical Affine Transformation.- Applications of Digital Holography for Information Security.- Gait-Based Human Identification Using Appearance Matching.- 2-D Periodic Patterns for Image Watermarking.- Image Steganalysis.- Public-Key Cryptography: An Overview of some Algorithms.

Image Steganography: Concepts and Practice

Abstract: In the last few years, we have seen many new and powerful steganography and steganalysis techniques reported in the literature. In the following tutorial we go over some general concepts and ideas that apply to steganography and steganalysis. We review and discuss the notions of steganographic security and capacity. Some of the more recent image steganography and steganalysis techniques are analyzed with this perspective, and their contributions are highlighted.

Increasing robustness of LSB audio steganography using a novel embedding method

Abstract: We present a novel high bit rate LSB audio watermarking method. The basic idea of the proposed LSB algorithm is watermark embedding that causes minimal embedding distortion of the host audio. Using the proposed two-step algorithm, watermark bits are embedded into higher LSB layers, resulting in increased robustness against noise addition or MPEG compression. Listening tests showed that the perceptual quality of watermarked audio is higher in the case of the proposed method than in the standard LSB method.

Significance of steganography on data security

Abstract: With the ever increasing amount and variety of data to be stored and transmitted in various mediums, the specification of security which has to be established at various levels of medium access and the accompanying issues of authentication and authorization has become a critical factor. Various steganographic, watermarking and data-embedding algorithms have usually manipulated the actual data in order to either hide any coveted information or to provide some level of access control over the medium. The mediums are usually images, video, audio etc., wherein specific portions or the overall space is usually 'corrupted' with 'significant' data. We attempt to bring out the significance of the steganographic techniques that are employed in information processing algorithms for data security. It deals with the problem of data security, focusing mainly on images, and tries to state the various properties and characteristics that the steganographic algorithms should possess. We also highlight the technique of masking used in the conventional steganographic LSB algorithms and in its variants.

An Overview of Steganography for the Computer Forensics Examiner

Abstract: Steganography is the art of covered or hidden writing. The purpose of steganography is covert communication-to hide the existence of a message from a third party. This paper is intended as a high-level technical introduction to steganography for those unfamiliar with the field. It is directed at forensic computer examiners who need a practical understanding of steganography without delving into the mathematics, although references are provided to some of the ongoing research for the person who needs or wants additional detail. Although this paper provides a historical context for steganography, the emphasis is on digital applications, focusing on hiding information in online image or audio files. Examples of software tools that employ steganography to hide data inside of other files as well as software to detect such hidden files will also be presented.

Public-Key Steganography

Abstract: Informally, a public-key steganography protocol allows two parties, who have never met or exchanged a secret, to send hidden messages over a public channel so that an adversary cannot even detect that these hidden messages are being sent. Unlike previous settings in which provable security has been applied to steganography, public-key steganography is information-theoretically impossible. In this work we introduce computational security conditions for public-key steganography similar to those introduced by Hopper, Langford and von Ahn [7] for the private-key setting. We also give the first protocols for public-key steganography and steganographic key exchange that are provably secure under standard cryptographic assumptions. Additionally, in the random oracle model, we present a protocol that is secure against adversaries that have access to a decoding oracle (a steganographic analogue of Rackoff and Simon’s attacker-specific adaptive chosen-ciphertext adversaries from CRYPTO 91 [10]).

Grey level modification steganography for secret communication

Abstract: Security, privacy, anti-virus, trusted computing, intrusion detection and information protection are major concerns in today's industrial informatics They are regarded as critical components for industrial based IT solutions (Zincheng, N et al,2003) Most industrial software systems rely on the third party vendors to provide the safeguards This approach in turn brings up a major issue regarding the trust of the third parties We often see that in one industrial system, there may be several other parties' trustees in order to provide all the security needs, in this paper, we describe an approach that can provide security and information protection through steganography, without a need for third party trustees We present a steganographic algorithm, which is an information hiding technique which allows secret communication, to cover and recover hidden information within the spatial domain of the image It has low computational complexity and high information hiding capacity The principle behind the algorithm is to embed information by modifying the grey level values of the grey scale image pixels We demonstrate this method by giving examples as proof of the concepts

Searching for the stego-key

Abstract: Steganalysis in the wide sense consists of first identifying suspicious objects and then further analysis during which we try to identify the steganographic scheme used for embedding, recover the stego key, and finally extract the hidden message. In this paper, we present a methodology for identifying the stego key in key-dependent steganographic schemes. Previous approaches for stego key search were exhaustive searches looking for some recognizable structure (e.g., header) in the extracted bit-stream. However, if the message is encrypted, the search will become much more expensive because for each stego key, all possible encryption keys would have to be tested. In this paper, we show that for a very wide range of steganographic schemes, the complexity of the stego key search is determined only by the size of the stego key space and is independent of the encryption algorithm. The correct stego key can be determined through an exhaustive stego key search by quantifying statistical properties of samples along portions of the embedding path. The correct stego key is then identified by an outlier sample distribution. Although the search methodology is applicable to virtually all steganographic schemes, in this paper we focus on JPEG steganography. Search techniques for spatial steganographic techniques are treated in our upcoming paper.

An improved sample pairs method for detection of LSB embedding

Abstract: This paper presents a fast algorithm to detect the least significant bit (LSB) steganography. Our approach is inspired by the work of Dumitrescu et al. [1] who detected LSB steganography via sample pair analysis. Our new algorithm combines with the statistical measures developed in [1] and a new least square estimation. The motivation comes from the high accuracy and robustness of the least square method used in parameter estimation. Plentiful experimental results show that our novel method has much lower false alarm rate of 5% than that of 13.79% in [1]. Meanwhile, the estimating precision of our algorithm is about 9% higher than that of the algorithm [1] if the embedding ratio is less than 10%, and the speed of our algorithm is also about 15% faster than the algorithm [1]. Some theoretical derivations are also included.

An improved sample pairs method for detection of LSB embedding

Abstract: This paper presents a fast algorithm to detect the least significant bit (LSB) steganography. Our approach is inspired by the work of Dumitrescu et al.[1] who detected LSB steganography via sample pair analysis. Our new algorithm combines with the statistical measures developed in [1] and a new least square estimation. The motivation comes from the high accuracy and robustness of the least square method used in parameter estimation. Plentiful experimental results show that our novel method has much lower false alarm rate of 5% than that of 13.79% in [1]. Meanwhile, the estimating precision of our algorithm is about 9% higher than that of the algorithm [1] if the embedding ratio is less than 10%, and the speed of our algorithm is also about 15% faster than the algorithm [1]. Some theoretical derivations are also included.