Rozlomii I. Methods and tools of counteracting falsifications of electronic documents

The dissertation is devoted to actual issues of developing new and improving existing methods and tools of counteracting falsifications of electronic documents. The cryptographic and steganographic tools of electronic documents protection such as electronic digital signature and digital watermark were consider in dissertation research. The research showed that electronic digital signature is one of the main mechanisms for ensuring the integrity and reliability of electronic documents. Thus, methods for calculating hash functions of electronic documents were construct. The research reveals solving the problem of ensuring the authenticity of electronic documents by developing methods for detecting falsifications. Methods of calculating hash functions were use to develop methods for finding false fragments in electronic documents. The method of complex use of electronic digital signature and digital watermark for an additional level of protection of electronic documents was proposed. The methods of calculating the hash functions of an electronic document based on using operations of matrix cryptographic transformation has been developed. The functional schemes of the methods of keyless calculation of the hash function of the electronic document were construct. Hash algorithms for each of the proposed schemes were develop. The algorithms with successive and parallel execution of operations of calculating the hash function were show. Modifications of algorithms for calculating hash functions were propose, which are improved by addition of operations of matrix cryptographic transformation. The methods of key hashing were develop, the result of which is the matrix, which is changed on the basis of analysis of the information of the electronic document. The method for detecting a false fragment of an electronic document by a method of cross-hashing has been developed. The method of cross-hashing is calculating hash functions in the vertical and horizontal blocks of the electronic document. This will allow to detect a false fragment of information on the intersection of blocks. The method of redundant hashing, which is based on Hamming's coding principle, has been further developed. This method ensures the guaranteed detection of several false fragments in electronic document based on the excessive hashing of the control block of information. The method for forming a conditional digital watermark based on operations of a matrix cryptographic transformation of values from a given interval, which determine the rules for the imposition of a digital watermark, was develop. The method of complex use of electronic digital signature and digital watermark in order to provide an additional level of protection of electronic documents was propose. The developed algorithms and functional schemes of the proposed methods will allow implementation of methods for their practical application.