Substitution box is the only nonlinear component in the block cipher. It cryptographic strength determines the se⁃curity of the whole cipher algorithm. A method of designing S⁃box based on genetic algorithm is proposed,then the properties, such as Bijection,Nonlinearity,Strict avalanche criterion,output bits independence,and difference uniformity are tested and analyzed. The result shows that the S⁃box using the algorithm has high cryptographic properties,which is suitable for developping block cipher algrithm.% S⁃box是分组密码中惟一的非线性部件,它的密码强度决定了整个分组密码的安全强度。提出了一种基于遗传算法的S⁃box设计方法,并对S⁃box的双射性、非线性度、严格雪崩准则、输出比特间独立性和差分均匀性进行了测试和分析。分析结果表明,利用该算法产生的S⁃box具有良好的密码学特性,适合用于开发新的分组密码算法。
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