【摘要】 对SHA-1算法的完备度、雪崩效应度、严格雪崩效应及抗碰撞性进行了逐拍统计分析。针对目前密码学界所揭示出的SHA-1设计缺陷,主要以增强SHA-1算法的非线性扩散特性及抗碰撞性为目标,对其进行改进。改进算法在混合函数中逆序使用改进后的扩展码字序列,并在算法首轮的混合函数中引入整数帐篷映射,加速了差分扩散,改变了原来固定的链接变量传递方式,修正了算法内部结构的设计缺陷。测试与分析结果表明,改进算法提高了非线性扩散程度,增强了算法的安全性。更多还原

【Abstract】 The degrees of completeness and avalanche effect and strict avalanche criterion for SHA-1 with increased number of steps were statistically analyzed.In order to improve the performance of collision resistance and nonlinear diffusion for SHA-1,the original algorithm was improved for its design defects and vulnerability indicated in the field of the current cryptology.The improved algorithm with mix function applied inverse message expansions sequence and inserted Integer tent maps at the first round of mix function,to accelerate differential diffusion,to alter the original linked variables passing method,to correct the inner design architecture defects of the algorithm.The test and analysis results proved the reforming algorithm improved the degrees of nonlinear diffusion and enhanced the security of the algorithm.更多还原