Kuznyechik

Кузнечик
Kuznyechik
Grasshopper

General
Designers	InfoTeCS JSC
First published	2015
Certification	GOST, and FSS
Cipher detail
Key sizes	256 bits Feistel network
Block sizes	128 bits
Structure	Substitution-permutation network
Rounds	10
Best public cryptanalysis
A meet-in-the-middle attack on 5 rounds.

Kuznyechik (Russian: Кузнечик) is a symmetric block cipher. It has a block size of 128 bits and key length of 256 bits. It is defined in the National Standard of the Russian Federation GOST R 34.12-2015 and also in RFC 7801.

The name of the cipher can be translated from Russian as grasshopper, however, the standard explicitly says that the English name for the cipher is Kuznyechik (/kʊznˈɛtʃɪk/). The designers claim that by naming the cipher Kuznyechik they follow the trend of difficult to pronounce algorithm names set up by Rijndael and Keccak.

The standard GOST R 34.12-2015 defines the new cipher in addition to the old GOST block cipher (now called Magma) one and does not declare the old cipher obsolete.

Kuznyechik is based on a substitution-permutation network, though the key schedule employs a Feistel network. The first block cipher with a mixed structure.

${\displaystyle \mathbb {F} }$ — Finite field ${\displaystyle GF(2^{8})}$ ${\displaystyle x^{8}+x^{7}+x^{6}+x+1}$.

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