A single-key attack on the full GOST block cipher

  • Authors:
  • Takanori Isobe

  • Affiliations:
  • Sony Corporation, Tokyo, Japan

  • Venue:
  • FSE'11 Proceedings of the 18th international conference on Fast software encryption
  • Year:
  • 2011

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Abstract

The GOST block cipher is the Russian encryption standard published in 1989. In spite of considerable cryptanalytic efforts over the past 20 years, a key recovery attack on the full GOST block cipher without any key conditions (e.g., weak keys and related keys) has not been published yet. In this paper, we show a first single-key attack, which works for all key classes, on the full GOST block cipher. To construct the attack, we develop a new attack framework called Reflection-Meet-inthe-Middle Attack. This approach combines techniques of the reflection attack and the meet-in-the-middle attack. We apply it to the GOST block cipher with further novel techniques which are the effective MITM techniques using equivalent keys on short rounds. As a result, a key can be recovered with 2225 computations and 232 known plaintexts.