代换密码

We provide a substitution box, exponential permutation which has much measurable security, and give a enumerating result and a fast algorithm of calculating such permutation. An almost perfect nonlinear exponential permutation with high algebric degree is proposed. with some discussion on how to select the parameters of such permutation. The experimental result shows us a conjecture that there exists no such permutation over even dimensional space. As a way of generating substitution boxes, we briefly point out the cryptographic weakness of the exponential functions derived from such permutation. We also present two new cryptographic indexes, fixed point and cyclic structure, on which we investigate the performance of such permutation. Finally, we give a viewpoint about the application of correlation immune functions in designing substitution boxes.

提供了一种可度量安全强度的代换盒－幂置换；详细阐述了幂置换的实现和计数问题；给出了一种计算幂置换的快速算法；从几乎完善非线性幂置换角度讨论了幂置换参数的选取，并提出了一种高次几乎完善非线性置换；通过试验给出了关于偶数维空间上几乎完善非线性幂置换的一个猜想；简要给出了由幂置换派生出的幂函数的密码局限性；针对幂置换，提出了两个密码安全指标：不动点和循环结构；证明了幂置换在这两个指标下的密码性能；简要讨论了相关免疫函数与代换盒设计的关系。

The S box was constituted with the multiplication inverse element affined transformation in GF(2) of all elements of limited field GF(28),with S box s nonlinear byte changed,ciphered text attained the ideal status of the even of difference and the linear of deviation,and increased the capability of the AES algorithm of anti beating the difference cipher of analysis and linear cipher of analysis.

S盒由有限域G F(28)上所有元素的乘法逆元及在域G F(2)上的仿射变换构成，经过S盒的非线性字节代换，密文的差分均匀性和线性偏差都达到较理想的状态，提高了A E S算法抗击差分密码分析及线性密码分析的能力。

In a typical example emphasized index of coincidence in Kerckhoff assumption to cryptanalyze the polyalphabetic substitution cipher, the Vigenère cipher for exemple.

针对一个典型实例重点讲解重合指数法在Kerckhoff假设下破解多表代换（以Vigenère密码为例）方面的应用。

Analyzed some correlation problem of using elliptic curve construct cryptosystem.Make the correlation counterchange on the elliptic curve that suitable for constructing the cryptosystem and the op eration on it. Analyzed and researched discrete logarithm problems of elliptic c urve suitable for cryptosystem.

文中分析研究了利用有限域上的椭圆曲线构建密码体制的相关问题，对于适于建立密码体制的一类椭圆曲线进行了相应的仿射代换和其运算的映射变换，对椭圆曲线构建密码体制的椭圆离散对数问题进行了分析研究。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。