Spectral analysis of ZUC-256

  • Jing Yang Dept. of Electrical and Information Technology, Lund University, Lund, Sweden
  • Thomas Johansson Dept. of Electrical and Information Technology, Lund University, Lund, Sweden
  • Alexander Maximov Ericsson Research, Lund, Sweden
Keywords: ZUC-256, Stream Cipher, 5G Mobile System Security

Abstract

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.

Published
2020-05-07
How to Cite
Yang, J., Johansson, T., & Maximov, A. (2020). Spectral analysis of ZUC-256. IACR Transactions on Symmetric Cryptology, 2020(1), 266-288. https://doi.org/10.13154/tosc.v2020.i1.266-288
Section
Articles