SNOW 3G stream cipher operation and complexity study

Abstract

SNOW 3G is a stream cipher algorithm that had been conceived and chosen in 2006 as the heart of the second set of UMTS con dentiality and integrity algorithms. It has been kept as the engine of the rst set of LTE cryptographic algorithms as well. The reason is that SNOW 3G respects properly the 3GPP requirements regarding the time and memory resources. This stream cipher is a two components stream cipher with an internal state of 608 bits initialized by a 128-bit key and a 128-bit initialization vector IV. In the present paper, we will interested rst in SNOW 3G algorithm structure, its components and then its two di erent operation modes. After that, we will focus on its e ciency by studying its time and space complexity.