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GOST 28147-89 (Magma) ¶

Algorithm type

Block cipher

Blocksize

64 bit

Keysize

256 bit

Structure

Feistel network

Rounds

32

RFC

• 5830
• 8891 (Magma)

Best attack

2²²⁴ with 2³² open-enciphered text pairs. Highly depends on used S-boxes

Wikipedia

article

Features:

• Was developed by KGB in USSR
• Standard does not define any S-boxes:
  • There could be backdoors in S-box, if it was defined and fixed by the standard.
  • Secret/private S-box could be used as an additional keying information.
  • You can not determine cipher’s strength without knowing the exact S-box. Self-made S-boxes can highly affect overall cipher’s strength.
  • Implementations using different S-boxes are not interoperable.
• You have to be very cautious using that cipher with that small blocksize and often do rekeying.
• "Magma" name was issued in Kuznechik standard. It is identical to GOST 28147-89, except for fixed S-boxes and slightly different key and block conversion.

Implementations: here.