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

Alex Biryukov, Dmitry Khovratovich, Léo Perrin
2017 IACR Transactions on Symmetric Cryptology  
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
more » ... w 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.
doi:10.13154/tosc.v2016.i2.226-247 dblp:journals/tosc/BiryukovKP16 fatcat:alfmeli7qbbw7j5w2gqwzpw2ki