Abstract. Among cryptographic algorithms, block encryption algorithms are used to reliably protect confidential information from unauthorized users. Many countries have established their own standards for block encryption algorithms. This, in turn, ensures reliable protection of information. And this is despite the fact that in Kazakhstan, standards for such information protection algorithms have not been approved. There, the creation of block encryption algorithms and the study of their cryptographic strength are always among the most pressing issues. This article presents the results of differential and statistical analysis of the block encryption algorithm «EM Chiper». One of the main methods for studying the strength of block encryption algorithms is statistical analysis of strength. If good mixing and diffusion is successfully implemented during the transformations commonly used in block ciphers, then a high level of cryptographic security of the algorithm can be achieved. To conduct statistical analysis, the algorithm was implemented in software and ciphertexts of various lengths were obtained. According to the conducted research, the statistical analysis of the proposed algorithm showed high results, that is, according to the requirements recommended by NIST, it was determined that the values in column A are greater than the values in C, and the values in B are greater than the values in D. The results of the differential analysis showed that the proposed algorithm has high cryptographic strength. That is, the probability of finding the key from round 16 is 2^(-126). In addition, the article conducted a comparative analysis of the results of the differential analysis of signature algorithms, and found that they showed comparable results with the well-known Camellia 128 and AES 128 algorithms. In future works, a comprehensive study of the cryptographic strength of other algorithms will be conducted, and the results will be presented in the form of an article.

Keywords. Block cipher, cipher, cryptography, key, differential cryptanalysis, statistical analysis, EM Chiper, S-block.