The stream cipher core of the 3GPP encryption standard 128-EEA3: Timing attacks and countermeasures

Abstract

The core of the 3 rd Generation Partnership Project (3GPP) encryption standard 128-EEA3 is a stream cipher called ZUC. It was designed by the Chinese Academy of Sciences and proposed for inclusion in the cellular wireless standards called Long Term Evolution or 4G. The LFSR-based cipher uses a 128-bit key. In this paper, we first show timing attacks on ZUC that can recover, with about 71.43% success rate, (i) one bit of the secret key immediately, and (ii) information involving 6 other key bits. The time, memory and data requirements of the attacks are negligible. While we see potential improvements to the attacks, we also suggest countermeasures. © 2012 Springer-Verlag Berlin Heidelberg.