Open AccessSpectral analysis of ZUC-256
Author(s) -
Jing Yang,
Thomas Johansson,
Alexander Maximov
Publication year - 2020
Publication title -
iacr transaction on symmetric cryptology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.715
H-Index - 10
ISSN - 2519-173X
DOI - 10.46586/tosc.v2020.i1.266-288
Subject(s) - computer science , linear cryptanalysis , key (lock) , cryptanalysis , higher order differential cryptanalysis , theoretical computer science , algorithm , entropy (arrow of time) , cryptography , computer security , physics , quantum mechanics
In this paper we develop a number of generic techniques and algorithms in spectral analysis of large linear approximations for use in cryptanalysis. We apply the developed tools for cryptanalysis of ZUC-256 and give a distinguishing attack with complexity around 2236. Although the attack is only 220 times faster than exhaustive key search, the result indicates that ZUC-256 does not provide a source with full 256-bit entropy in the generated keystream, which would be expected from a 256-bit key. To the best of our knowledge, this is the first known academic attack on full ZUC-256 with a computational complexity that is below exhaustive key search.