Date : 07 juin 2019 à 09:15 — 15 min.
It is crucial for a cipher to be trusted that its design be well explained. However, some designers do not publish their design method and instead merely put forward a specification. While this information is sufficient for implementers, the lack of explanation hinders third party cryptanalysis.
In a recent string of papers, Biryukov, Perrin and Udovenko identified increasingly strong patterns in a subcomponent shared by the last two Russian standards in symmetric cryptography, namely the hash function Streebog (GOST R 34.11-2012) and the block cipher Kuznyechik (GOST R 34.12-2015). In this paper, we summarize the latest result of Perrin on this topic and argue that, in light of them, these algorithms must be avoided.