Paper 2021/1134

Some observations on ZUC-256

Alexander Maximov

Abstract

In this report we study efficient binary approximations of the FSM of ZUC-256 with high correlation around $2^{-21.1}$ between the keystream words and the LFSR. We then map these approximations into a binary distinguisher with complexity around $2^{234}$. Thereafter, we convert to an approximation in the LFSR's field $\mathbb{Z}_p$ with correlation around $2^{-33.6}$. We share a number of observations and state open problems for further research and considerations.

Note: The report is updated with more results and observations.