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2012年,Keccak在SHA-3算法竞赛中脱颖而出成为SHA-3算法标准.自此之后对Keccak算法的分析成为研究热点.本文探究的是对缩减轮Keccak杂凑函数的差分区分器攻击.在已有研究中,Sourav和Meier等提出了一种6轮的Keccak区分器,该区分器基于TDA算法、Double Kernel结构和Keccak内部置换的差分传播特性,得到的区分器复杂度为2~(52).本文在上述结果的基础上,首先改进了Willi Meier等提出的差分路径,得到了一个更优的6轮差分区分器,该结果为目前已知最好的6轮差分区分器,数据复杂度为2~(28);接着文章探究7轮的差分区分器,按照新的差分路径,文章得到了新的7轮差分区分器,但是因为在差分路径中Keccak内部函数的扩散作用,增大了得到该差分路径的数据复杂度.文章通过对于S盒性质的分析,提出了一种S盒控制技术,通过忽略一些对结果中的偏置位没有影响的S盒,能够很好地降低得到该区分器的数据复杂度,从而保证在7轮之后的输出中存在偏置位,得到了一个复杂度为2~(68)的7轮Keccak区分器.
Keccak became the SHA-3 algorithm standard in the SHA-3 algorithm contest in 2012. Since then, the analysis of Keccak algorithm has become a research hotspot.This paper explores the differential discriminator attack on the reduced round Keccak hash function, In the research, Sourav and Meier et al. Proposed a 6-round Keccak divider with 2 ~ (52) divider complexity based on the differential propagation characteristics of TDA algorithm, Double Kernel structure and Keccak internal permutation. Based on the above results, this paper improves the differential path proposed by Willi Meier et al. And obtains a better 6-round differential differentiator. The result is the best known 6-round differential differentiator with the data complexity of Then the article explores seven differential differentiators. According to the new differential path, a new seven-differential differentiator is obtained. However, due to the diffusion of Keccak’s intrinsic function in the differential path, The data complexity of the differential path.Through analyzing the properties of S-boxes, this paper presents a S-box control technique, which can be well reduced by neglecting some S-boxes that have no influence on the bias bits in the result The complexity of the data, so as to ensure the presence of offset bits output after 7 to give a complexity of 2 ~ (68) 7 Keccak distinguisher.