Description: There is a need to develop methods that can provide an effective attack on the linguistic stegosystem in modern realities. Attack based on semantic compression is the most effective mean of counteracting any method of textual steganography for the purpose of removing the stegomessages. However, there is a problem associated with the computerization of the process. The article describes the method of the textual information semantic compression for counteracting computer linguistic steganography, consisting of five consecutive stages (automated linguistic analysis of the text, evaluating its comprehension and allocation of the basic meaning, compression, modification and formation of the final text after making changes) based on the discursive analysis, which is determined by the adaptation of the summarization methods to take into account the possible steganography means to the attack the linguistic stegosystem by semantic compressing of both, meaningful and automatically generated texts. The method is based on usage of an integrated approach and takes into account a wide range of steganography methods. It was developed using probability theory, mathematical statistics and simulation, set theory, the method of solving tasks using Euler circles, morphological (the logical multiplication method), syntactic (probabilistic-statistical method) and discourse analysis (textual-intertextual approach); summarization methods and comprehensions writing ways, elements of intensional logic and formal grammar. The proposed method is the basis for automating the attack on the linguistic stegosystem by semantic compression and further program implementation. The functionality provided by the method, namely the compression of sentences and large texts, a wide range of research, the detection of automatically generated texts, taking into account the semantics and the possibility of removing the stegomessage during the compression, open a wide range of further practical application of the method in complex computer steganographic and steganoanalytic systems and attacks on a linguistic stegosystem based on the use of natural (English) language in its basis.
Keywords: computer linguistic steganography, semantic compression of the text, textual steganalysis, automated steganalysis, method of textual compression, determination of the textual meaningfulness, attack on the linguistic stegosystem