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针对以单圈T函数代替线性移位寄存器设计流密码的可行性,对单圈T-函数的分量函数所生成序列(第k位序列)的移位自相关性进行了研究.在移位量取第k位序列周期与2的负指数幂之积的条件下,根据单圈T函数的性质,结合自相关函数的周期特征,计算了对应的自相关函数的上界和下界.由该上下界分析知,当移位量较小时,自相关函数的取值较大,表明T函数不适合直接用作密码函数生成伪随机序列.
Aiming at the feasibility of designing a stream cipher using a single-turn T-function instead of a linear shift register, the shift autocorrelation of a sequence (kth bit sequence) generated by a component function of a single-turn T-function is studied. The upper and lower bounds of the corresponding autocorrelation function are calculated based on the properties of the monotactic T-function and the periodic features of the autocorrelation function, taking the product of the k-th sequence period and the negative exponent power of 2. From this upper and lower The boundary analysis shows that when the shift amount is small, the value of the autocorrelation function is larger, indicating that the T function is not suitable for directly generating the pseudorandom sequence by the cryptographic function.