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Steganography methods are considered to be one of the most common technologies for the protection of any digital data when transmitted over open communication channels at a given time. The solution of the problem of digital data protection using steganography methods is used not only by government services, but also by terrorist organizations. Therefore, the need for research, development and continuous improvement of steganoanalytical methods is becoming extremely important. The steganoanalytical algorithm based on the study of the singular decomposition of digital image matrix blocks is proposed in the paper. The main purpose of this paper is to increase the efficiency of digital image steganoanalysis, in the absence of a container, by developing a new steganoanalytical algorithm based on the study of the singular decomposition of digital image matrix blocks. As a result of a detailed study of the steganography algorithm using the singular decomposition of digital image matrix blocks, the statistical characteristics of the singular values of image matrix blocks are established. Based on the defined characteristics, the paper presents the main steps of the stegananoanalytical algorithm. As a criterion for assessing the effectiveness of the developed steganoanalytical algorithm, the probability of detecting additional information was used. Errors of the first and second type are considered. To compare the results of the developed steganoanalytical algorithm with existing algorithms in open access, the following applications are selected: XSteg; StegSpy. The software product "StegoAnalysis" has been implemented for the automated solution of the stegananalytical problem for digital image. [ABSTRACT FROM AUTHOR]

Due to the growth of computer crime, an important and urgent problem is the development of methods for detecting the integrity violations of a digital image. In particular, the detection of different types of the image post-processing after their possible forgery is a grey area of information security, and the detection of processing by the Sharpen Filter is an issue practically not covered in open scientific literature. The artificial sharpening of a digital image is the reverse procedure to the blurring. Previously, the authors of the paper developed the method for detecting blur of a digital image based on an analysis of the growth rate of singular values. When blurring, the growth rate of singular values is an order of magnitude smaller than before the blurring, which makes it possible to reveal a threshold value for detecting blurred images. The singular values increase accordingly to the artificially sharpening. But it is not possible to reveal the threshold value in this case. The aim of this paper is to identify the parameters of the digital image matrix, which indicate an artificial sharpening, and to develop a method for detecting sharpness as a digital image post-processing. If the contour is considered as a change in the brightness function of a digital image, then the change in the brightness function will be faster when the contours are sharpened. If two adjacent pixels had the close sharpness values before sharpening, then applying this filter will increase the difference between them. In this paper, the investigation of the close color pairs of an image is carried out when the Sharpness Filter was applied to it. It is revealed that the number of close color pairs during processing decreases. The threshold value which allows separating the processed image from the raw one is empirically established. The method of detecting sharpness as a digital image postprocessing is developed based on the results obtained. [ABSTRACT FROM AUTHOR]

The protection of electronic information by cryptographic and steganographic methods, as well as their combination, is in great demand today. However, the new type of steganography - hash-steganography, fundamentally differs from classical steganography in that there is no need to embed messages in a container, no need to worry about the amount of information that can be transmitted in one container without compromising the visual stability of the image. A certain sequence of ordinary digital images is a message. The purpose of this work is to increase the efficiency of transmitting a secret message by modifying the hash-method of steganography. Previously, algorithms for obtaining hash functions of digital images have not been used to transmit messages, but they have found their application in hash-steganography. This paper compares two algorithms for obtaining hash codes and suggests a method of their application for transforming a text message into a sequence of digital images. It is a certain order of files transferred that is decisive in the decryption of a message. The symbols of the message are put in correspondence with the part of the hash code of the digital image. Thus, the necessary combination of files is formed, the number of which is equal to the number of symbols in the message. A comparative analysis of the two algorithms of the method has been performed. The results obtained have confirmed the effectiveness of the hash code algorithm based on the analysis of digital image DCT coefficients. This algorithm makes the method resistant to attack by compression, changing brightness and contrast, magnification and rotation. [ABSTRACT FROM AUTHOR]

In this paper we study the effect of perturbing influences aimed at the spatial domain of digital images on the change of color triplets in the matrix of unique colors of a digital image. In the course of computational experiments established that the modification of only blue color matrix of the image, the quantity of Blue-triads (which indicate the blue color component of the image) in the matrix of unique colors of the digital image significantly exceeds the quantity of Red- and Green-triads that will allow for the examination of images clearly establish the fact of modifying the blue color component. The identified feature is typical for most containers in a lossy format which is associated with the digital image's formation technologies and compression algorithms therefore despite the low sensitivity of the human eye to blue color it is not recommended to use the blue color component for spatial transformations of the image, in particular, for steganographic transformations. During the experiments the most suitable for spatial transformations green and red color components revealed, since their modifications lead to the appearance of a smaller quantity of Green- and Red-triads (which indicate the green and red color components of the image, respectively) and to obtain a comparable quantity of all types of triads of triplets in a matrix of unique colors which will complicate the correct examination of a digital image from the point of view of unambiguously identifying a modified color component. The obtained results are substantiated from the standpoint of color perception by the human eye, which underlies the formation of colors by digital cameras, and the image compression features of the JPEG standard. Criteria for determining the color component of a digital image providing less disturbance in the quantity of sequential triads in a matrix of unique colors and the basic steps for determining for a particular image the most and least suitable for steganographic transformation color components in terms of changes in color triplets in a matrix of unique colors are given. [ABSTRACT FROM AUTHOR]

The use of the digital images in modern society is very common, making it difficult to name an industry where digital images are not used. However, in certain situations, the digital images may be direct or indirect digital evidence, such as in court cases. Tampering or violating the integrity of the digital images is one of the important issues in the information protection. The issue of the digital signal authentication by cybersecurity experts is a pressing issue in the present days. Therefore, the development of methods and algorithms for detecting the integrity of digital signals in general, and digital images in particular, is a very crucial task. Among all the possible variations in the integrity violation of digital images can be distinguished a separate group, in which the digital images are processed by various filters editors, such as blurring, sharpening, etc. The blurring is often applied to images not only when they are tampered, but also as a steganographic attack. Blur detection indicates the inability to use a digital image as the evidence of anything. One of the most effective blur detection methods known from the open sources is a method based on the analysis of singular values of blocks of a digital image matrix. The aim of this paper is to increase the efficiency of the blur detection in a digital image by modifying an algorithm based on the analysis of singular values. Computational experiments are performed to determine the number of parameters to be verified. The results obtained allow modifying the algorithm of the method of the blur detection in a digital image. The modification makes it possible to detect tampered access to a digital image. The modified algorithm is no less effective than the original algorithm, and allows analyzing fewer parameters in a shorter time. The computational complexity of the algorithm is determined by the second order polynomial that is acceptable in terms of the practical application. [ABSTRACT FROM AUTHOR]

Photos are an integral and certainly an important part of our lives. Often we are faced with a need to increase the clarity of digital image, for example, solving pattern recognition problems, or for other reasons. Methods of increasing the clarity of digital images are very diverse, each has its own range of applicability. However, there may be often artifacts by processing of digital image. The aim of this paper is to increase clarity of digital image with the possibility of avoiding artifacts. To achieve this aim the researchers used digital image processing algorithms, based on using different convolution matrix types. There are shown in typical images with increasing clarity of digital image what advantages is the use of combinations of these algorithms in a specific sequence. A comparative analysis of the impact of different filters to increase the clarity of digital images was conducted and gives recommendations by using them. [ABSTRACT FROM AUTHOR]