Focusing on the problem whether there are new security flaws of several kinds of high-level cryptographic S-boxes,an algorithm for solving the nonlinear invariant function of S-boxes was proposed,which is mainly based on the algebraic relationship between the input and output of the cryptographic S-boxes.Using the proposed algorithm,several kinds of S-boxes were tested and it was found that several of them had the same nonlinear invariant function.In addition,if these S-boxes were used to non-linear parts of the block cipher Midori-64,a new variant algorithm would be obtained.The security analysis was carried out by non-linear invariant attack.The analytical results show that the Midori-64 variant is faced with serious secure vulnerability.In other words,there exist 264 weak keys when nonlinear invariant attack is applied to the Midori-64 variant,meanwhile data,time and storage complexity can be neglected,consequently some high-level cryptographic S-boxes have security flaws.%针对几类高强度密码S盒是否存在新的安全性漏洞问题,提出了一种求解S盒非线性不变函数的算法.该算法主要基于密码S盒输入和输出的代数关系来设计.利用该算法对这几类密码S盒进行测试,发现其中几类存在相同的非线性不变函数;此外,如果将这些S盒使用于分组密码Midori-64的非线性部件上,将会得到一个新的变体算法.利用非线性不变攻击对其进行安全性分析,结果表明:该Midori-64变体算法存在严重的安全漏洞,即在非线性不变攻击下,存在264个弱密钥,并且攻击所需的数据、时间及存储复杂度可忽略不计,因此这几类高强度密码S盒存在新的安全缺陷.
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