STUDY OF THE PARAMETERS OF THE DIGITAL CONTENT MATRIX BLOCKS IN DIFFERENT STORAGE FORMATS AS A THEORETICAL BASIS FOR THE METHODS OF DETECTING VIOLATIONS OF ITS INTEGRITY

Abstract

Unauthorized changes of digital information contents, in particular images, videos, which are considered in the work, the detection of which is a difficult and urgent task, require the development of new approaches and methods. In case of unauthorized changes in digital contents, there is often a change in the format (lossy/lossless) of its preservation (in whole or in part), in particular when organizing a steganographic communication channel, photomontage, etc. Thus, the identification of the fact of re-preservation of digital content in a format different from the original one is a pointer to the violation of its integrity, making the task of separating content in different formats urgent. The aim of the work is to study the properties of the formal parameters of blocks of original digital content to create a theoretical basis for the methods of separating content in various storage formats. In the course of the study: the formal parameters – the smallest singular values of the blocks of the corresponding matrices, based on the properties of which the proposal to introduce a formal research object – the matrix of the smallest singular values of the blocks, corresponding to the digital content and having properties that differ depending on from the digital content storage format – were determined; for a sequence of digital images of the same format, for digital video, a formal mathematical object is defined – a histogram of modes of histograms of matrices of the smallest singular values of blocks of images/frames of video, the properties of which differ significantly for different storage formats, which can be used to develop an appropriate expert method. Establishing quantitative characteristics for qualitative separators obtained in the work will provide an opportunity to form effective methods of separating digital contents in various storage formats, which can be applied as a component of the steganalysis process, in the process of detecting the results of photomontage, where contents in various formats were involved, etc.