Showing papers on "Steganography published in 2001"

Defending against statistical steganalysis

Abstract: The main purpose of steganography is to hide the occurrence of communication. While most methods in use today are invisible to an observer's senses, mathematical analysis may reveal statistical anomalies in the stego medium. These discrepancies expose the fact that hidden communication is happening. This paper presents improved methods for information hiding. One method uses probabilistic embedding to minimize modifications to the cover medium. Another method employs error-correcting codes, which allow the embedding process to choose which bits to modify in a way that decreases the likelihood of being detected. In addition, we can hide multiple data sets in the same cover medium to provide plausible deniability. To prevent detection by statistical tests, we preserve the statistical properties of the cover medium. After applying a correcting transform to an image, statistical steganalysis is no longer able to detect the presence of steganography. We present an a priori estimate to determine the amount of data that can be hidden in the image while still being able to maintain frequency count based statistics. This way, we can quickly choose an image in which a message of a given size can be hidden safely. To evaluate the effectiveness of our approach, we present statistical tests for the JPEG image format and explain how our new method defeats them.

Reliable detection of LSB steganography in color and grayscale images

Abstract: A large number of commercial steganographic programs use the Least Significant Bit embedding (LSB) as the method of choice for message hiding in 24-bit, 8-bit color images, and grayscale images. It is commonly believed that changes to the LSBs of colors cannot be detected due to noise that is always present in digital images. In this paper, we describe a new very accurate and reliable method that can detect LSB embedding in randomly scattered pixels in both 24-bit color images and 8-bit grayscale or color images. It is based on our previous work on lossless data embedding [1]. By inspecting the differences in the number of regular and singular groups for the LSB and the "shifted LSB plane", we can reliably detect messages as short as 0.03bpp.

Analysis of LSB based image steganography techniques

Abstract: There have been many techniques for hiding messages in images in such a manner that the alterations made to the image are perceptually indiscernible. However, the question whether they result in images that are statistically indistinguishable from untampered images has not been adequately explored. We look at some specific image based steganography techniques and show that an observer can indeed distinguish between images carrying a hidden message and images which do not carry a message. We derive a closed form expression of the probability of detection and false alarm in terms of the number of bits that are hidden. This leads us to the notion of steganographic capacity, that is, how many bits can we hide in a message without causing statistically significant modifications? Our results are able to provide an upper bound on the this capacity. Our ongoing work relates to adaptive steganographic techniques that take explicit steps to foil the detection mechanisms. In this case we hope to show that the number of bits that can be embedded increases significantly.

Digital steganography: hiding data within data

Abstract: Digital steganography is the art of inconspicuously hiding data within data. Steganography's goal in general is to hide data well enough that unintended recipients do not suspect the steganographic medium of containing hidden data. The software and links mentioned in this article are just a sample of the steganography tools currently available. As privacy concerns continue to develop along with the digital communication domain, steganography will undoubtedly play a growing role in society. For this reason, it is important that we are aware of digital steganography technology and its implications. Equally important are the ethical concerns of using steganography and steganalysis. Steganography enhances rather than replaces encryption. Messages are not secure simply by virtue of being hidden. Likewise, steganography is not about keeping your message from being known - it's about keeping its existence from being known.

Information Hiding: Steganography and Watermarking—Attacks and Countermeasures

Abstract: List of Figures. List of Tables. Preface. 1. Introduction. 2. Exploring Steganography. 3. Steganalysis: Attacks Against Hidden Data. 4. Counter Measures to Attacks. Appendix A: Hiding Data in Network Traffic. Appendix B: Glossary of Methods to Distort Stego-Images. References. Index.

An Implementation of Key-Based Digital Signal Steganography

Abstract: A real-life requirement motivated this case study of secure covert communication. An independently researched process is described in detail with an emphasis on implementation issues regarding digital images. A scheme using stego keys to create pseudo-random sample sequences is developed. Issues relating to using digital signals for steganography are explored. The terms modified remainder and unmodified remainder are defined. Possible attacks are considered in detail from passive wardens and methods of defeating such attacks are suggested. Software implementing the new ideas is introduced, which has been successfully developed, deployed and used for several years without detection.

Distortion-Free Data Embedding for Images

Abstract: One common drawback of virtually all current data embedding methods is the fact that the original image is inevitably distorted by some small amount of noise due to data embedding itself. This distortion typically cannot be removed completely due to quantization, bit-replacement, or truncation at the grayscales 0 and 255. Although the distortion is often quite small, it may not be acceptable for medical imagery (for legal reasons) or for military images inspected under unusual viewing conditions (after filtering or extreme zoom). In this paper, we introduce a general approach for high-capacity data embedding that is distortion-free (or lossless) in the sense that after the embedded information is extracted from the stego-image, we can revert to the exact copy of the original image before the embedding occurred. The new method can be used as a powerful tool to achieve a variety of non-trivial tasks, including distortion-free robust watermarking, distortion-free authentication using fragile watermarks, and steganalysis. The proposed concepts are also extended to lossy image formats, such as the JPG.

An additive approach to transform-domain information hiding and optimum detection structure

Abstract: This paper presents an additive approach to transform-domain information hiding and the performance analysis for images and video. The watermark embedding method is designed to satisfy the perceptual constraints and improve the detectability as well as the information embedding rate. The statistical behaviors of subband coefficients are modeled by the generalized Gaussian distribution. The structure of the optimum detection is built and the performance of the exact asymptotic detection is evaluated using large deviation theory. Our approach can not only achieve good transparency but also precisely control the detection errors. It can be applied to watermarking, authentication, fingerprinting, and steganography.

Steganalysis based on JPEG compatibility

Abstract: In this paper, we introduce a new forensic tool that can reliably detect modifications in digital images, such as distortion due to steganography and watermarking, in images that were originally stored in the JPEG format. The JPEG compression leave unique fingerprints and serves as a fragile watermark enabling us to detect changes as small as modifying the LSB of one randomly chosen pixel. The detection of changes is based on investigating the compatibility of 8x8 blocks of pixels with JPEG compression with a given quantization matrix. The proposed steganalytic method is applicable to virtually all steganongraphic and watermarking algorithms with the exception of those that embed message bits into the quantized JPEG DCT coefficients. The method can also be used to estimate the size of the secret message and identify the pixels that carry message bits. As a consequence of our steganalysis, we strongly recommend avoiding using images that have been originally stored in the JPEG format as cover-images for spatial-domain steganography.

Steganography: Past, Present, Future

Abstract: Steganography (a rough Greek translation of the term Steganography is secret writing) has been used in various forms for 2500 years. It has found use in variously in military, diplomatic, personal and intellectual property applications. Briefly stated, steganography is the term applied to any number of processes that will hide a message within an object, where the hidden message will not be apparent to an observer. This paper will explore steganography from its earliest instances through potential future application.

A Practical and Effective Approach to Large-Scale Automated Linguistic Steganography

Abstract: Several automated techniques exist to transform ciphertext into text that "looks like" natural-language text while retaining the ability to recover the original ciphertext. This transformation changes the ciphertext so that it doesn't attract undue attention from, for example, attackers or agencies or organizations that might want to detect or censor encrypted communication. Although it is relatively easy to generate a small sample of quality text, it is challenging to be able to generate large texts that are "meaningful" to a human reader and which appear innocuous.This paper expands on a previous approach that used sentence models and large dictionaries of words classified by part-of-speech [7]. By using an "extensible contextual template" approach combined with a synonymbased replacement strategy, much more realistic text is generated than was possible with NICETEXT.

SVD-Based Approach to Transparent Embedding Data into Digital Images

Abstract: A new approach to transparent embedding of data into digital images is proposed. It provides a high rate of the embedded data and is robust to common and some intentional distortions. The developed technique employs properties of the singular value decomposition (SVD) of a digital image. According to these properties each singular value (SV) specifies the luminance of the SVD image layer, whereas the respective pair of singular vectors specifies image geometry. Therefore slight variations of SVs cannot affect the visual perception of the cover image. The proposed approach is based on embedding a bit of data through slight modifications of SVs of a small block of the segmented covers. The approach is robust because it supposes to embed extra data into low bands of covers in a distributed way. The size of small blocks is used as an attribute to achieve a tradeoff between the embedded data rate and robustness. An advantage of the approach is that it is blind. Simulation has proved its robustness to JPEG up to 40%. The approach can be used both for hidden communication and watermarking.

Steganalysis of watermarking techniques using image quality metrics

Abstract: In this paper, we present techniques for steganalysis of images that have been potentially subjected to a watermarking algorithm. Our hypothesis is that a particular watermarking scheme leaves statistical evidence or structure that can be exploited for detection with the aid of proper selection of image features and multivariate regression analysis. We use some sophisticated image quality metrics as the feature set to distinguish between watermarked and unwatermarked images. To identify specific quality measures, which provide the best discriminative power, we use analysis of variance (ANOVA) techniques. The multivariate regression analysis is used on the selected quality metrics to build the optimal classifier using images and their blurred versions. The idea behind blurring is that the distance between an unwatermarked image and its blurred version is less than the distance between a watermarked image and its blurred version. Simulation results with a specific feature set and a well-known and commercially available watermarking technique indicates that our approach is able to accurately distinguish between watermarked and unwatermarked images.

Steganographic image processing

Abstract: Multi-bit auxiliary information is hidden in imagery (e.g., digital photographs, video), using steganographic techniques. Such information can be used for various purposes, including identifying an image as originating from a particular source. In some embodiments, certain bits of the auxiliary information effect no change to the image. A variety of different arrangements are disclosed.

Secure and invisible data hiding in 2-color images

Abstract: In an earlier paper, we propose a steganography scheme for hiding a piece of critical information in a host binary image. That scheme ensures that in each m/spl times/n image block of the host image, as many as [log/sub 2/(mn+1)] bits can be hidden in the block by changing at most 2 bits in the block. As a sequel of that work, in this paper we propose a revised scheme that can maintain higher quality of the host image by sacrificing some data hiding space. The new scheme can still offer a good data hiding ratio. It ensures that for any bit that is modified in the host image, the bit is adjacent to another bit which has a value equal to the former's new value. Thus, the hiding effect is quite invisible.

Independent component analysis applied to digital image watermarking

Abstract: The authors propose a new solution to the watermarking of digital images. This approach uses independent component analysis (ICA) to project the image into a basis with its components as statistically independent as possible. The watermark is then introduced in this representation of the space. Thus, the change of basis is the key of the steganography problem. The algorithm applied to the fragile watermarking problem locates any change in the image since it also applies to the watermark. The problem of robust watermarking is also addressed from this new point of view. Some results are included to illustrate the method.

MP3 resistant oblivious steganography

Abstract: Robustness to compression is a basic requirement for any data hiding scheme. We concentrate on MP3 resistant oblivious data hiding. First the MP3 compression algorithm is briefly introduced. We then propose three effective data hiding schemes, where the message is embedded in amplitude, DFT phase domain, and noisy components, respectively. All these schemes demonstrate robustness to MP3 compression.

A new paradigm hidden in steganography

Abstract: : We discuss how steganography, in contrast to similar disciplines, requires a new paradigm based upon discontinuities and the absence of noise as a detection deterrent.

Video error correction using steganography

Abstract: The transmission of any data is always subject to corruption due to errors, but video transmission, because of its real time nature must deal with these errors without retransmission of the corrupted data. The error can be handled by using forward error correction in the encoder or error concealment techniques in the decoder. The MPEG-2 compliant coder described here uses steganography to transmit data for error correction in conjunction with several error concealment techniques in the decoder. The decoder resynchronizes more quickly with fewer errors than traditional resynchronization techniques. This provides for a much higher quality picture in an error-prone environment while creating an almost imperceptible degradation of the picture in an error free environment.

Steganography decoding methods employing error information

Abstract: Media content, such as imagery (including video) and audio, can be encoded to convey hidden information (steganographic encoding) for a variety of purposes, including communication of auxiliary information (e.g., copyright data), authentication, tamper detection, forensic tracking, etc. The reading (decoding) of the hidden information from the media content is complicated if the content has been corrupted in some manner. One example of corruption is the lossy compression/decompression associated with JPEG processing of digital imagery. In some cases, the corruption introduces errors in the decoding. In other cases, the corruption prevents the hidden information from being decoded at all. In accordance with a preferred embodiment of the invention, reliable decoding of steganographically encoded information is enhanced by processing the corrupted media content so as to counteract some of the corruption. In accordance with another embodiment, the reading proceeds from the corrupted media content, but the results are processed in accordance with the corruption to which the content has been subjected.

A novel approach for increasing security and data embedding capacity in images for data hiding applications

Abstract: Data hiding in multimedia is the process of secretly embedding information into data sources such as image, video, or audio signals without changing the perceptual quality of the data source. We present a novel blind data hiding technique for hiding information in still images. This technique is based on embedding the information in the transform domain, after decorrelating the samples in the spatial domain. This results in a significant increase in the number of transform coefficients that can be used to transmit the hidden information. The technique is suitable for a variety of data hiding applications such as steganography, data authentication and captioning. The technique achieves a higher and more secure data embedding rate than existing data embedding transform domain techniques developed for these particular applications.

Secure blind image steganographic technique using discrete Fourier transformation

Abstract: We present a new steganographic technique for covert communications. The technique embeds the hidden information in the DFT domain after permuting the image pixels in the spatial domain using a key. The permutation process introduces randomness into the cover image and results in a significant increase in the number of transform coefficients that can be used to transmit the hidden information. The hidden information is embedded using a quantization technique. The perceptual and statistical properties of the cover and the stego images remain similar for small quantization steps. The security of the system is examined against known stego attack.

Audio signal watermarking based on replica modulation

Abstract: In this paper we present a brief overview of techniques for digital watermarking of audio signals, including basic requirements and typical applications. We propose a novel technique, based on replica modulation with correlation extraction, including several variations. The proposed method is characterized by excellent audio quality vs. robustness tradeoff, high bit rate, low processing load, and particularly good security.

DNA-based steganography

Abstract: This paper presents an implementation of steganography using DNA molecules. We first encode a plaintext message into a DNA sequence using a randomly generated single-substitution key. An oligonucleotide containing the encoded message, designated the message strand, is synthesized and mixed with a large amount of background DNA. To retrieve the message, the intended recipient must know the sequences of two primers that anneal to target regions present on the message strand. Polymerase chain reaction (PCR) and sequencing are used to retrieve the encoded sequence, which is decoded into the original plaintext via the single substitution key. This study shows that the steganographically hidden message can be retrieved only by using the two secret primers, meaning that the only applicable cryptanalytic approach is a brute-force search for the two primer sequences. Since each primer can have 420 different possible sequences, the amount of time required to crack DNA-based steganography is long enough to qualify t...

Steganographic watermarking for documents

Abstract: Defines digital seals for documents, their scope, application environment and limitations. These seals can be used to insert information into documents, as with watermarking, or to use documents as a communication channel for sending concealed messages, as is the goal of steganography. Users can decide to employ one or another functionality, or a combination of them, depending on their needs or preferences. As a step towards these objectives, a system was developed which constitutes a kit with several sealing options. The system writes either visible or invisible marks in digital documents, following the different methods designed and created in this project. These marks or seals, in turn, can be viewed through a seal recognizer. The implementation is done in RTF (rich text format), which is a commercial, massively accessible format.

Multiple-description framework for oblivious watermarking

Abstract: It is believed that digital watermarking can be a powerful tool that can be used to protect digital contents from illegal copying and distribution. Detecting the presence/absence of a watermark in a given digital content such as image/video data without using the unwatermarked orignial data is called oblivious watermark detection and the watermarking process is oblivious watermarking. Oblivious watermarking has many important practical applications such as secure video streaming or wireless image/video transmission where the intended receiver typically has access only to the received data. We propose for the first time a multiple description framework for oblivious watermarking. Parallels between multiple description source coding and the watermarking are drawn. An information theoretic definition of the problem is given. A spread-spectrum watermarking algorithm for DCT based multiple descriptions is described. Performance of the proposed framework for various attack channels such as additive white Gaussian noise, JPEG compression, and random bit error channels shows that the proposed method performs reasonably well compared to non-oblivious schemes. We believe the proposed framework can be further improved in conjunction with other methods such as error control coding. This framework can find applications in scalable watermarking (such as scalable video coding), rate controlled multimedia multicasting, secure wireless transmission, watermarking for distributed storage, and packet networks.

Steganography effects in various formats of images. A preliminary study

Abstract: In this paper, the effects of steganography in different image formats (BMP, GIF, JPEG and DWT coded) are studied. With respect to these formats, we try to give an answer to the following questions. (1) How many bits of noise (i.e. the textual secret message) can be injected without perceptually deteriorating the quality of the image? (2) How and where should one inject these bits in order to achieve the best trade-off in terms of the length of the textual message and the preserved quality of the image?.