In this paper we present results of algebraic analysis of GOSTt algorithm in SageMath environment. Using the GOSTt as the example we explore basic stages of algebraic analysis of any symmetric block cipher based on Feistel network. We construct sets of boolean equations for five encryption rounds and determine the number of known text pairs for which the key can be found with the probability of 1. The algebraic analysis of five rounds of GOSTt allowed to find a 160-bit encryption key with the probability of 1 for five known text pairs within 797.21 s; the search for the solution took 24.66 s.
['Ludmila K. Babenko', 'Ekaterina Maro', 'Maxim Anikeev']
Modeling of Algebraic Analysis of GOST+ Cipher in SageMath