Multiset-Algebraic Cryptanalysis of Reduced Kuznyechik, Khazad, and secret SPNs

  • Alex Biryukov Interdisciplinary Centre for Security, Reliability and Trust (SnT), Computer Science and Communications Research Unit (CSC), University of Luxembourg, Luxembourg, Luxembourg
  • Dmitry Khovratovich University of Luxembourg, Luxembourg, Luxembourg
  • Léo Perrin Interdisciplinary Centre for Security, Reliability and Trust (SnT), University of Luxembourg, Luxembourg, Luxembourg
Keywords: Generic SPN, Algebraic attack, Multi-set, Integral, Division property, Kuznyechik, Khazad

Abstract

We devise the first closed formula for the number of rounds of a blockcipher with secret components so that these components can be revealed using multiset, algebraic-degree, or division-integral properties, which in this case are equivalent. Using the new result, we attack 7 (out of 9) rounds of Kuznyechik, the recent Russian blockcipher standard, thus halving its security margin. With the same technique we attack 6 (out of 8) rounds of Khazad, the legacy 64-bit blockcipher. Finally, we show how to cryptanalyze and find a decomposition of generic SPN construction for which the inner-components are secret. All the attacks are the best to date.

Published
2017-02-03
How to Cite
Biryukov, A., Khovratovich, D., & Perrin, L. (2017). Multiset-Algebraic Cryptanalysis of Reduced Kuznyechik, Khazad, and secret SPNs. IACR Transactions on Symmetric Cryptology, 2016(2), 226-247. https://doi.org/10.13154/tosc.v2016.i2.226-247
Section
Articles