Papers by kaushal solanki
We present practical approaches for steganography that can provide improved security by closely m... more We present practical approaches for steganography that can provide improved security by closely matching the second-order statistics of the host rather than just the marginal distribution. The methods are based on the framework of statistical restoration, wherein a fraction of the host symbols available for hiding is actually used to restore the statistics; thus reducing the rate, but providing security against steganalysis. We establish correspondence between steganography and the earth-mover's distance (EMD), a popular distance metric used in computer vision applications. The EMD framework can be used to define the optimum flow (modifications) of the host symbols for compensation. This formulation is used for image steganography by restoring the second-order statistics of the blockwise discrete cosine transform (DCT) coefficients. Some practical limitations of this approach (such as computational complexity and difficulty in dealing with overlapping coefficient pairs) are noted, and a new method is proposed that alleviates these deficiencies by identifying the coefficients to modify based on a local compensation criterion. Experimental results on several thousand natural images demonstrate the utility of the presented methods.
We consider the problem of hiding images in images. In addition to the usual design constraints s... more We consider the problem of hiding images in images. In addition to the usual design constraints such as imperceptible host degradation and robustness in presence of variety of attacks, we impose the condition that the quality of the recovered signature image should be better if the attack is milder. We present a simple hybrid analogdigital hiding technique for this purpose. The signature image is compressed efficiently (using JPEG) into a sequence of bits, which is hidden using a previously proposed digital hiding scheme. The residual error between the original and compressed signature image is then hidden using an analog hiding scheme. The results show (perceptual as well as mean-square error) improvement as the attack becomes milder.
Information Hiding, 10th International Workshop, IH 2008, Santa Barbara, CA, USA, May 19-21, 2008, Revised Selected Papers
... Organizing Committee General Chair Organization Kaushal Solanki Mayachitra Inc., USA Program ... more ... Organizing Committee General Chair Organization Kaushal Solanki Mayachitra Inc., USA Program Chairs Kenneth Sullivan Upamanyu Madhow Mayachitra Inc., USA University of California, SantaBarbara, USA Program Committee Ross Anderson Mauro Barni Patrick Bas ...
Information-theoretic analysis for data hiding prescribe embedding the hidden data in the choice ... more Information-theoretic analysis for data hiding prescribe embedding the hidden data in the choice of quantizer for the host data. In this paper, we consider a suboptimal implementation of this prescription, with a view to hiding high volumes of data in images with low perceptual degradation. The three main findings are as follows: (i) Scalar quantization based data hiding schemes incur about 2 dB penalty from the optimal embedding strategy, which involves vector quantization of the host. (ii) In order to limit perceivable distortion while hiding large amounts of data, hiding schemes must use local perceptual criteria in addition to information-theoretic guidelines. (iii) Powerful erasure and error correcting codes provide a flexible framework that allows the data-hider freedom of choice of where to embed without requiring synchronization between encoder and decoder.
Robust image-adaptive data hiding based on erasure and error correction
IEEE Transactions on Image Processing, 2004
This paper provides a summary of our work over the past two years on robust, high-volume data hid... more This paper provides a summary of our work over the past two years on robust, high-volume data hiding in images. We first present a basic framework for imageadaptive hiding, which allows selection of the coefficients in which to hide, and employs powerful "turbo-like" erasures and errors codes in a novel manner to prevent desynchronization of encoder and decoder due to selective embedding. This coding framework provides robustness against a variety of attacks, including compression, tampering and moderate resizing. Next, we provide a joint source-channel coding scheme for image-in-image hiding, in which the quality of the recovered signature image is better if the attack is milder. This is achieved by hybrid digital-analog hiding. Finally, we present preliminary results on hiding techniques that survive printing and scanning. The techniques are devised after experimental modeling of the print-scan channel.
In this paper, we present a framework for the design of steganographic schemes that can provide p... more In this paper, we present a framework for the design of steganographic schemes that can provide provable security by achieving zero Kullback-Leibler divergence between the cover and the stego signal distributions, while hiding at high rates. The approach is to reserve a number of host symbols for statistical restoration: host statistics perturbed by data embedding are restored by suitably modifying the symbols from the reserved set. A dynamic embedding approach is proposed, which avoids hiding in low probability regions of the host distribution. The framework is applied to design practical schemes for image steganography, which are evaluated using supervised learning on a set of about 1000 natural images. For the presented JPEG steganography scheme, it is seen that the detector is indeed reduced to random guessing.
In steganography (the hiding of data into innocuous covers for secret communication) it is diffic... more In steganography (the hiding of data into innocuous covers for secret communication) it is difficult to estimate how much data can be hidden while still remaining undetectable. To measure the inherent detectability of steganography, Cachin [1] suggested the c-secure measure, where c is the Kullback Leibler (K-L) divergence between the cover distribution and the distribution after hiding. At zero divergence, an optimal statistical detector can do no better than guessing; the data is undetectable. The hider's key question then is, what hiding rate can be used while maintaining zero divergence? Though work has been done on the theoretical capacity of steganography, it is often difficult to use these results in practice. We therefore examine the limits of a practical scheme known to allow embedding with zero-divergence. This scheme is independent of the embedding algorithm and therefore can be generically applied to find an achievable secure hiding rate for arbitrary cover distributions.
This paper proposes a method to hide information into images that achieves robustness against pri... more This paper proposes a method to hide information into images that achieves robustness against printing and scanning with blind decoding. A significant contribution of this paper is a technique to estimate and undo rotation. The method is based on the fact that laser printers use an ordered digital halftoning algorithm for printing. Using the proposed hiding method, several hundred information bits can be embedded into 512×512 images with perfect recovery against the print-scan operation. Moreover, the hidden images also survive other attacks such as Gaussian or median filtering, scaling or aspect ratio change, heavy JPEG compression, and rows and/or columns removal.
Further study on YASS: steganography based on randomized embedding to resist blind steganalysis
We present further extensions of yet another steganographic scheme (YASS), a method based on embe... more We present further extensions of yet another steganographic scheme (YASS), a method based on embedding data in randomized locations so as to resist blind steganalysis. YASS is a JPEG steganographic technique that hides data in the discrete cosing transform (DCT) coefficients of randomly chosen image blocks. Continuing to focus on JPEG image steganography, we present, in this paper, a further study on YASS with the goal of improving the rate of embedding. Following are the two main improvements presented in this paper: (i) a method that randomizes the quantization matrix used on the transform domain coefficients, and (ii) an iterative hiding method that utilizes the fact that the JPEG "attack" that causes errors in the hidden bits is actually known to the encoder. We show that using both these approaches, the embedding rate can be increased while maintaining the same level of undetectability (as the original YASS scheme). Moreover, for the same embedding rate, the proposed steganographic schemes are more undetectable than the popular matrix embedding based F5 scheme, using features proposed by Pevny and Fridrich for blind steganalysis.
In steganography (the hiding of data into innocuous covers for secret communication) it is diffic... more In steganography (the hiding of data into innocuous covers for secret communication) it is difficult to estimate how much data can be hidden while still remaining undetectable. To measure the inherent detectability of steganography, Cachin [1] suggested thesecure measure, where is the Kullback Leibler (K-L) divergence between the cover distribution and the distribution after hiding. At zero divergence, an optimal statistical detector can do no better than guessing; the data is undetectable. The hider's key question then is, what hiding rate can be used while maintaining zero divergence? Though work has been done on the theoretical capacity of steganography, it is often difficult to use these results in practice. We therefore examine the limits of a practical scheme known to allow embedding with zero-divergence. This scheme is independent of the embedding algorithm and therefore can be generically applied to find an achievable secure hiding rate for arbitrary cover distributions.
IEEE Transactions on Image Processing, 2004
Information-theoretic analyses for data hiding prescribe embedding the hidden data in the choice ... more Information-theoretic analyses for data hiding prescribe embedding the hidden data in the choice of quantizer for the host data. We propose practical realizations of this prescription for data hiding in images, with a view to hiding large volumes of data with low perceptual degradation. The hidden data can be recovered reliably under attacks, such as compression and limited amounts of image tampering and image resizing. The three main findings are as follows. 1) In order to limit perceivable distortion while hiding large amounts of data, hiding schemes must use image-adaptive criteria in addition to statistical criteria based on information theory. 2) The use of local criteria to choose where to hide data can potentially cause desynchronization of the encoder and decoder. This synchronization problem is solved by the use of powerful, but simple-to-implement, erasures and errors correcting codes, which also provide robustness against a variety of attacks. 3) For simplicity, scalar quantization-based hiding is employed, even though information-theoretic guidelines prescribe vector quantization-based methods. However, an information-theoretic analysis for an idealized model is provided to show that scalar quantization-based hiding incurs approximately only a 2-dB penalty in terms of resilience to attack.
IEEE Transactions on Information Forensics and Security, 2006
Print-scan resilient data hiding finds important applications in document security and image copy... more Print-scan resilient data hiding finds important applications in document security and image copyright protection. This paper proposes methods to hide information into images that achieve robustness against printing and scanning with blind decoding. The selective embedding in low frequencies scheme hides information in the magnitude of selected low-frequency discrete Fourier transform coefficients. The differential quantization index modulation scheme embeds information in the phase spectrum of images by quantizing the difference in phase of adjacent frequency locations. A significant contribution of this paper is analytical and experimental modeling of the print-scan process, which forms the basis of the proposed embedding schemes. A novel approach for estimating the rotation undergone by the image during the scanning process is also proposed, which specifically exploits the knowledge of the digital halftoning scheme employed by the printer. Using the proposed methods, several hundred information bits can be embedded into images with perfect recovery against the print-scan operation. Moreover, the hidden images also survive several other attacks, such as Gaussian or median filtering, scaling or aspect ratio change, heavy JPEG compression, and rows and/or columns removal
A new, simple, approach for active steganography is proposed in this paper that can successfully ... more A new, simple, approach for active steganography is proposed in this paper that can successfully resist recent blind steganalysis methods, in addition to surviving distortion constrained attacks. We present Yet Another Steganographic Scheme (YASS), a method based on embedding data in randomized locations so as to disable the self-calibration process (such as, by cropping a few pixel rows and/or columns to estimate the cover image features) popularly used by blind steganalysis schemes. The errors induced in the embedded data due to the fact that the stego signal must be advertised in a specific format such as JPEG, are dealt with by the use of erasure and error correcting codes. For the presented JPEG steganograhic scheme, it is shown that the detection rates of recent blind steganalysis schemes are close to random guessing, thus confirming the practical applicability of the proposed technique. We also note that the presented steganography framework, of hiding in randomized locations and using a coding framework to deal with errors, is quite simple yet very generalizable.
Obtaining Higher Rates for Steganographic Schemes While Maintaining the Same Detectability
This paper focuses on modifying the decoder module for an active steganographic scheme to increas... more This paper focuses on modifying the decoder module for an active steganographic scheme to increase the effective data-rate without affecting the embedding module. Three techniques are suggested to improve the error correction framework of an active steganographic scheme. The first involves puncturing where the code-length is increased by adding a suitable number of additional erasures. The second technique involves channel modeling and soft-decision decoding which is adaptive to the embeddable image coefficient. The third method adjusts the erasure threshold depending on the design hiding quantizer so as to achieve a higher data-rate. Combining these techniques, the effective data-rate is increased by 10%-50% for Yet Another Steganographic Scheme (YASS), a popular active steganographic scheme.
Print-scan resilient data hiding finds important applications in document security, and image cop... more Print-scan resilient data hiding finds important applications in document security, and image copyright protection. In this paper, we build upon our previous work on print-scan resilient data hiding with the goal of providing a simple mathematical characterization for guiding the design of more sophisticated methods allowing higher volume of embedded data, or achieving more robustness. A model for print-scan process is proposed, which has three main components: a) effects due to mild cropping, b) colored high-frequency noise, and c) non-linear effects. It can be shown that cropping introduces unknown phase shift in the image spectrum. A new hiding method called Differential Quantization Index Modulation (DQIM) is proposed in which, information is hidden in the phase spectrum of images by quantizing the difference in phase of adjacent frequency locations. The unknown phase shift would get cancelled when the difference is taken. Using the proposed DQIM hiding in phase, we are able to survive the print-scan process with several hundred information bits hidden into the images.
In this paper, we present a framework for the design of steganographic schemes that can provide p... more In this paper, we present a framework for the design of steganographic schemes that can provide provable security by achieving zero Kullback-Leibler divergence between the cover and the stego signal distributions, while hiding at high rates. The approach is to reserve a number of host symbols for statistical restoration: host statistics perturbed by data embedding are restored by suitably modifying the symbols from the reserved set. A dynamic embedding approach is proposed, which avoids hiding in low probability regions of the host distribution. The framework is applied to design practical schemes for image steganography, which are evaluated using supervised learning on a set of about 1000 natural images. For the presented JPEG steganography scheme, it is seen that the detector is indeed reduced to random guessing.
In this paper we present methods for scene understanding, localization and classification of comp... more In this paper we present methods for scene understanding, localization and classification of complex, visually heterogeneous objects from overhead imagery. Key features of this work include: determining boundaries of objects within large field-of-view images, classification of increasingly complex object classes through hierarchical descriptions, and exploiting automatically extracted hypotheses about the surrounding region to improve classification of a more localized region. Our system uses a principled probabilistic approach to classify increasingly larger and more complex regions, and then iteratively uses this automatically determined contextual information to reduce false alarms and misclassifications.
Information-theoretic analyses for data hiding prescribe embedding the hidden data in the choice ... more Information-theoretic analyses for data hiding prescribe embedding the hidden data in the choice of quantizer for the host data. In this paper, we consider a suboptimal implementation of this prescription, with a view to hiding high volumes of data in images with low perceptual degradation. Our two main findings are as follows: (a) In order to limit perceptual distortion while hiding large amounts of data, the hiding scheme must use perceptual criteria in addition to information-theoretic guidelines. (b) By focusing on "benign" JPEG compression attacks, we are able to attain very high volumes of embedded data, comparable to information-theoretic capacity estimates for the more malicious Additive White Gaussian Noise (AWGN) attack channel, using relatively simple embedding techniques.
We investigate data hiding techniques that attempt to defeat steganalysis by restoring the statis... more We investigate data hiding techniques that attempt to defeat steganalysis by restoring the statistics of the composite image to resemble that of the cover. The approach is to reserve a number of host symbols for statistical restoration: host statistics perturbed by data embedding are restored by suitably modifying the symbols from the reserved set. While statistical restoration has broad applicability to a variety of hiding methods, we illustrate our ideas here for quantization index modulation (QIM) based hiding. We propose a method for significantly reducing the detectability of QIM, while preserving its robustness to attacks. We next use the framework of statistical restoration to develop a method to combat steganalysis techniques which detect block-DCT embedding by evaluating the increase in blockiness of the image due to hiding. Numerical results demonstrating the efficacy of these techniques are provided.
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Papers by kaushal solanki