Guess and Determine Attack on SNOW3G and ZUC
Jie Guan, Lin Ding, Shu-Kai LIU · Journal of Software · 2014
SNOW3G 流密码算法是3G Partnership Project(3GPP)中实现数据保密性和数据完整性的标准算法UEA2&UIA2 的核心,ZUC 是3GPP 中加密算法128-EEA3 和完整性保护算法128-EIA3 的核心.至今还没有针对SNOW3G 进行猜测决定攻击的研究结果出现.对SNOW3G 进行了猜测决定攻击,其计算复杂度为2320,所需数据量为9 个32 比特密钥字.通过对ZUC 算法设计的分析,将ZUC 算法中基于32 比特字的非线性函数转化为基于16 比特半字的非线性函数,提出了基于16 比特半字的猜测决定攻击,其计算复杂度为2392,所需数据量为9 个32 比特密钥字,该结果优于已有的针对ZUC 的猜测决定攻击.分析结果表明,尽管ZUC 算法的内部状态规模小于SNOW3G,在抵抗猜测决定攻击方面,ZUC 明显优于SNOW3G.;SNOW3G stream cipher is the core of the standardized 3G Partnership Project (3GPP) confidentiality and integrity algorithms UEA2 & UIA2 while ZUC stream cipher is the core of the standardized 3GPP confidentiality and integrity algorithms 128-EEA3 & 128-EIA3. So far, there have been no Guess and Determine attacks applied to SNOW3G. In this paper, a Guess and Determine attack on SNOW3G is proposed with a computational complexity of 2320, requiring 9 keystream words (each word consists of 32 bits). After analyzing the design of ZUC, a half-word-based Guess and Determine attack on ZUC is introduced, based on transforming the word-based nonlinear function of ZUC into a half-word-based nonlinear function. The attack on ZUC has a computational complexity of 2392 and requires 9 keystream words, which is better than the previous Guess and Determine attack on ZUC. These results show that ZUC has much better resistance against Guess and Determine attack than SNOW 3G, though the internal state size of ZUC is smaller than SNOW 3G.