SHA-3的安全性分析

Security analysis of SHA-3

为分析hash函数新标准SHA-3算法的安全性,从算法统计性能和轮函数Keccak-f的对称性两个方面对其进行测试。测试结果表明,SHA-3算法雪崩效应良好,平均变化比特数和平均变化概率都非常接近理想值且方差比较小,具有较高的稳定性和较低的碰撞程度;Keccak-f中添加常数的变换会严重扰乱轮函数的对称性,利用轮函数对称性对SHA-3进行内部差分攻击只适用于轮数较少的情况。

In order to evaluate the new hash standard SHA-3,this paper conducted a security analysis of it from the perspective of statistical performance and symmetrical property of round permutation Keccak-f. The results show that SHA-3 possesses favorable avalanche effect,and average number of changed bits and average probability of changed bits are both very close to the ideal value with a small standard deviation. It has high stability and low collision degree. The ι mapping which was used to add round constants could seriously disrupt the symmetry of Keccak-f. Thus,internal differential attack could only be achieved in a limited numbers of rounds.