New results in a research of GOST R 34.12-2015

The new symmetric block encryption standard GOST R34.12-2015 came into force in Russian Federation on January 1^st, 2016. The standard defines two encryption algorithms. One of those is a former standard encryption algorithm GOST 29147-89 (also known as simply GOST) with fixed S-boxes. This algorithm is denoted as Magma in the new standard. Magma is a symmetric block cipher based on Feistel scheme with 64-bit blocks, 256-bit secret key, and 32 processing rounds. The second algorithm is a new symmetric block cipher based on SP-network, which is denoted as Kuznyechik. In this paper, we consider few problems. First, we are consider the possibility to reduce encryption time of each data block by applying special precomputed tables. Then we are offering to consider possible ways to apply slide analysis to Magma and “Kusnyechik” ciphers. Further study we focused on s the study of Magma and Kuzhyechik strength using such analysis techniques as linear cryptanalysis, differential cryptanalysis, impossible differential cryptanalysis and the related-key attack method.