Dual image based LSB steganography

Abstract: Pixel value differencing (PVD) and Least Significant Bit (LSB) embedding are well known spatial domain steganographic techniques. PVD utilizes the sharp changes of intensities among adjacent pixels where a large number of secret bits could be embedded without any perceptible change. one-time pad (OTP) symmetric cryptography is known for its security. In the proposed scheme one or more LSB bits of the selected pixels are used depending on the pixel intensity difference with neighboring pixels in 2 × 2 image blocks of the cover image. Secret bits are encrypted using OTP with randomly generated pre-shared key. Such encrypted bits are completely random and resemble noise hence make the scheme robust against different statistical attacks. Comparative simulations with some well-known PVD-based techniques show good results in terms of visual imperceptibility and different quality metrics such as MSE, PSNR, SSIM etc.

Abstract: Text steganography is inherently difficult due to minimal redundant information space to hide secret payload. The same fact limits the hiding capacity and security too. In this study, a novel technique has been proposed using a randomized indexed word dictionary, and a list of email addresses to increase the hiding capacity and security. A forward email platform has been used as the cover, and email addresses in the carbon copy (CC) field contain secret data that are encoded using a randomized index-based word dictionary. The email username list and indexed word dictionary are both pre-shared between the communicating parties. But during every new communication, a random bitstream (temporary stego-key) is generated from the system time and communicated separately using public-key cryptography. This temporary stego-key is used to randomize the index values of the words in the dictionary. Most of the existing state-of-the-art techniques provide a hiding capacity of 6–10%. The proposed scheme achieves a capacity of 12.17% using some common secret text and email body text (cover text) as used in all other studies. The proposed technique provides higher hiding capacity and security by randomizing the word indexes every time using temporary stego-key. It is also free from statistical attacks, OCR based attacks, and does not depend on the use of any particular text processor.

Abstract: In the modern digital era, the privacy of personal communication is a serious concern to all netizens. A better way to preserve privacy could be to hide the secret message inside some innocent looking digital object such as image, audio, video, etc., which is known as steganography. A new steganographic scheme using a reference image along with the cover image has been proposed in this article. It enhances the robustness and security by increasing the obscurity of the hidden message. It also employs an additional dictionary-based encoding module to increase the hiding capacity as well as security. Experiments show that bit changes in the reference image are very few and undetectable to human perception, it also evades common statistical tests. Evaluation of standard quality parameters such as MSE, PSNR, UIQI, SSIM along with chi-squared statistics based embedding probability testing has been performed. When dictionary-based encoding is applied it further improves the quality parameters.

Abstract: In spatial domain image steganography, Least Significant Bits (LSB) of cover image pixels are used to embed a secret message due to minimal distortion and higher payload capacity. In this paper, we have introduced an exclusive-OR (XOR) based encoding of encrypted secret message bits using varying higher-order pixel intensity bits. Encoding and LSB embedding is done block-wise by dividing the cover image into a number of blocks. The secret message is first encrypted using symmetric key cryptography and then encoded those encrypted bits by XORing them with randomly selected higher-order pixel bis of the cover image to obscure the secret bits further. Next, an inversion technique is applied to the encoded bits block-wise to keep the LSB bit changes to a minimum. The stego-key consists of the symmetric encryption key and the encode-key containing parameter settings such as the number_of_blocks, starting_block, start_pixel_offset, block_selection_rule, etc. This stego-key is shared prior to the actual communication using public-key cryptography to ensure the key’s authenticity and integrity. The extraction process does not require the cover image; the stego-image and the stego-key are sufficient. Experimental results show the visual imperceptibility along with improved image quality metrics such as Mean Square Error (MSE), Peak Signal to Noise Ratio (PSNR), Normalized Cross-Correlation (NCC), and Structural Similarity (SSIM) index in comparison to other well-known techniques. The average PSNR value remains above 51dB, even with 90% of the capacity utilized. The proposed scheme successfully eludes many standard steganalysis attacks such as histogram-based analysis (PDH), chi-square based embed probability test, Regular and Singular groups (RS) analysis, sample pair test, etc. on the tested stego-images.

Abstract: Steganography is the science that involves communicating secret data in an appropriate multimedia carrier, e.g., image, audio, and video files. It comes under the assumption that if the feature is visible, the point of attack is evident, thus the goal here is always to conceal the very existence of the embedded data. Steganography has various useful applications. However, like any other science it can be used for ill intentions. It has been propelled to the forefront of current security techniques by the remarkable growth in computational power, the increase in security awareness by, e.g., individuals, groups, agencies, government and through intellectual pursuit. Steganography's ultimate objectives, which are undetectability, robustness (resistance to various image processing methods and compression) and capacity of the hidden data, are the main factors that separate it from related techniques such as watermarking and cryptography. This paper provides a state-of-the-art review and analysis of the different existing methods of steganography along with some common standards and guidelines drawn from the literature. This paper concludes with some recommendations and advocates for the object-oriented embedding mechanism. Steganalysis, which is the science of attacking steganography, is not the focus of this survey but nonetheless will be briefly discussed.

Abstract: A new and efficient steganographic method for embedding secret messages into a gray-valued cover image is proposed. In the process of embedding a secret message, a cover image is partitioned into non-overlapping blocks of two consecutive pixels. A difference value is calculated from the values of the two pixels in each block. All possible difference values are classified into a number of ranges. The selection of the range intervals is based on the characteristics of human vision's sensitivity to gray value variations from smoothness to contrast. The difference value then is replaced by a new value to embed the value of a sub-stream of the secret message. The number of bits which can be embedded in a pixel pair is decided by the width of the range that the difference value belongs to. The method is designed in such a way that the modification is never out of the range interval. This method provides an easy way to produce a more imperceptible result than those yielded by simple least-significant-bit replacement methods. The embedded secret message can be extracted from the resulting stego-image without referencing the original cover image. Moreover, a pseudo-random mechanism may be used to achieve secrecy protection. Experimental results show the feasibility of the proposed method. Dual statistics attacks were also conducted to collect related data to show the security of the method.

Abstract: An information-theoretic model for steganography with passive adversaries is proposed. The adversary’s task of distinguishing between an innocent cover message C and a modified message S containing a secret part is interpreted as a hypothesis testing problem. The security of a steganographic system is quantified in terms of the relative entropy (or discrimination) between P C and P S. Several secure steganographic schemes are presented in this model; one of them is a universal information hiding scheme based on universal data compression techniques that requires no knowledge of the covertext statistics.

Abstract: In this paper, we develop a novel method to embed important data in the host image so that the interceptors will not notice about the existence of the data. The basic concept of the proposed method is by simple LSB substitution. To prevent illicit access of data and increase the system performance, the method of randomized process and the optimal LSB substitution are proposed. The e!ectiveness of the optimal LSB substitution in the worst case is proved. We also develop a genetic algorithm to solve the problem of hiding important data in the rightmost k LSBs of the host image, which may involve a huge computation time to "nd the optimal result when k is large. Finally, based on the concept of perceptual modeling, an improved hiding technique is developed to obtain a high-quality embedding result. Experimental results will reveal that the quality of the embedding result will not be seriously degraded, and is near optimal by utilizing the proposed method. ( 2001 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.

Abstract: Steganography is the art of hiding the fact that communication is taking place, by hiding information in other information. Many different carrier file formats can be used, but digital images are the most popular because of their frequency on the Internet. For hiding secret information in images, there exists a large variety of steganographic techniques some are more complex than others and all of them have respective strong and weak points. Different applications have different requirements of the steganography technique used. For example, some applications may require absolute invisibility of the secret information, while others require a larger secret message to be hidden. This paper intends to give an overview of image steganography, its uses and techniques. It also attempts to identify the requirements of a good steganographic algorithm and briefly reflects on which steganographic techniques are more suitable for which applications.