利用Dobbertin指数构造低差分均匀度函数

有限域上多项式型的低差分均匀度函数在分组密码的非线性组件S盒中有着重要的作用.为了增强S盒的混淆作用,应用在S盒中的函数应具有较高的非线性度和较高的代数次数.文章通过改变Dobbertin类的单项式函数在有限域F_(2n)的一个子域上的函数值,构造了两类新的多项式型的低差分均匀度函数,并确定了这两类多项式型函数的代数次数和第二类函数的非线性度.     

Galois环和Z/(m)环上完全非线性函数的性质

本文把完全非线性函数推广到了有限Abel群上,利用特征谱讨论了Z/(m)上Bent函数与GF(pe)上bent函数以及完全非线性函数定义之间的关系;给出Galois环与Z/(m)上最佳线性逼近的特征谱表示,得到完全非线性函数在某种程度上能抵抗最佳线性逼近攻击的结论;并给出一种Galois环与Z/(m)环上完全非线性函数的构结方法.     

一类多项式型的超bent函数

Bent函数是一类著名的布尔函数,它们具有偶数个变元和最大的非线性度,并且在密码、编码和序列设计方面有着广泛的应用.超bent函数是bent函数的一个重要的子类,并且具有最大的代数次数.本文提出了一类多项式型的超bent函数,利用与Dickson多项式相关的完全指数和、Kloosterman和以及Weil和刻画了这类函...     

亚纯函数的非线性微分多项式分担多项式的唯一性

研究了亚纯函数的某类非线性微分多项式弱分担一个多项式的唯一性问题,得到两个亚纯函数的唯一性定理,推广了Li和Yi(Comput Math Appl,2011,62:539-550),Chen和Zhang等(Comput Math Appl,2008,56:3000-3014)所得的结果.     

特征为2的有限域上的一类差分4一致函数

有限域上的低差分一致性函数在密码学中有着重要的应用背景.目前人们发现的特征为2的有限域上的差分4一致函数并不是很多.通过交换定义在有限域F_2~n上的Kasami几乎完全非线性函数x~(2~(2k)—2~k+1)任意两点之间的取值,给出了一类新的差分4一致函数;并在n为奇数的情况下,证明了所给出的这类函数是具有较高非线性度和代数次数的置换函数.     

特征为2的有限域上的一类差分4一致函数北大核心CSCD

有限域上的低差分一致性函数在密码学中有着重要的应用背景.目前人们发现的特征为2的有限域上的差分4一致函数并不是很多.通过交换定义在有限域F_2~n上的Kasami几乎完全非线性函数x^(2^(2k)—2~k+1)任意两点之间的取值,给出了一类新的差分4一致函数;并在n为奇数的情况下,证明了所给出的这类函数是具有较高非线性度和代数次数的置换函数.     

航空器供油问题中完全逆序类中的多项式时间可解类

航空器供油问题是一类非线性组合优化问题,其目标函数为分式形式,该问题目前不存在多项式时间算法,也未被证明是NP完全问题。一般可以用置换来刻画n架飞机的一个供油顺序。该问题中有一类实例被称为“完全逆序类”,“完全逆序类”用动态规划算法求解计算时间为O(n2ⁿ),具有指数时间复杂度。本文通过对该“完全逆序类”问题做进一步分析,发现在“完全逆序类”中也存在着多项式时间可解的情况。定理1研究一类一次可解的情况,若问题满足定理1的条件,则求解一次即可找到其最优解;定理2研究一类多项式时间可解的情况,当问题满足定理2的条件时,其最优解可在多项式时间内获得。     

切换多项式非线性系统的输入-状态稳定性

利用耗散不等式研究了切换多项式非线性系统的输入-状态稳定性分析问题,在任意切换信号下,给出了使得切换多项式非线性系统输入-状态稳定的充分条件.采用平方和分解方法来寻找切换多项式非线性系统的输入-状态稳定共同Lyapunov函数.数值算例验证了所提方法的可行性.     

A Space-Time Polynomial Collocation Method for Solving 3D Burgers Equations北大核心CSCD

Burgers方程是一类应用广泛的非线性偏微分方程,方程中的非线性项难以处理。该文提出一种新的时空多项式配点法——多项式特解法求解三维Burgers方程。求解过程分为两步:第一步,对三维Burgers方程中的线性导数项(包括时间导数项),求出相应的多项式特解。第二步,将求出的多项式特解作为基函数,对三维Burgers方程中剩余的非线性项进行迭代求解。与时空多项式函数作为基函数对三维Burgers方程进行直接求解相比,该算法简单易行,得到的近似解精度非常高,算法极其稳定,对于教学过程中提高学生的编程能力,加深对高维Burgers方程的理解能力以及Burgers方程的实际应用具有重要意义。     

多项式形的静态非线性投入产出模型解的存在性研究

经济系统时常表现明显的非线性特征，研究非线性投入产出具有重要的现实意义。在假定直接消耗系数是关于部门总产品的多项式函数的条件下，利用不动点理论求得在一定条件下，静态非线性投入产出模型的解的范围。由于多项式函数具有分段区间单词性的特点，使得多项式型的非线性投入产出模型突破了以往的研究中要求直接消耗系数仅仅是关于部门总产品的单调递减或单调递增的函数的限制，使建立非线性投入产出模型的条件更为宽松，更能描述现实的经济系统。     

On the classification of APN functions up to dimension five

We classify the almost perfect nonlinear (APN) functions in dimensions 4 and 5 up to affine and CCZ equivalence using backtrack programming and give a partial model for the complexity of such a search. In particular, we demonstrate that up to dimension 5 any APN function is CCZ equivalent to a power function, while it is well known that in dimensions 4 and 5 there exist APN functions which are not extended affine (EA) equivalent to any power function. We further calculate the total number of APN functions up to dimension 5 and present a new CCZ equivalence class of APN functions in dimension 6.     

On equivalence between known polynomial APN functions and power APN functions

Constructions and equivalence of APN functions play a significant role in the research of cryptographic functions. On finite fields of characteristic 2, 6 families of power APN functions and 14 families of polynomial APN functions have been constructed in the literature. However, the study on the equivalence among the aforementioned APN functions is rather limited to the equivalence in the power APN functions. Meanwhile, the theoretical analysis on the equivalence between the polynomial APN functions and the power APN functions, as well as the equivalence in the polynomial APN functions themselves, is far less studied. In this paper, we give the theoretical analysis on the inequivalence in 8 known families of polynomial APN functions and power APN functions.     

Notes on APN functions, semibiplanes and dimensional dual hyperovals

Two geometric objects, incidence graphs of semibiplanes and dimensional dual hyperovals, are respectively associated with APN and quadratic APN functions. From Proposition 2 (resp. Proposition 5), two APN (resp. quadratic APN) functions are CCZ (resp. extended affine) equivalent if and only if the associated graphs (resp. dimensional dual hyperovals) are isomorphic. The former graphs for almost bent functions are distance regular graphs by Proposition 4. The structures of automorphism groups of these geometric objects are investigated in Proposition 3 and Lemma 7. In particular, (Edel and Pott, Adv Math Commun 3:59–81 (2009), Question 2) is negatively answered.     

More constructions of APN and differentially 4-uniform functions by concatenation

We study further the method of concatenating the outputs of two functions for designing an APN or a differentially 4-uniform (n, n)-function for every even n. We deduce several specific constructions of APN or differentially 4-uniform (n, n)-functions from APN and differentially 4-uniform (n/2, n/2)-functions. We also give a construction of quadratic APN functions which includes as particular cases a previous construction by the author and a more recent construction by Pott and Zhou.     

On the symmetric properties of APN functions

We study the symmetric properties of APN functions as well as the structure and properties of the range of an arbitrary APN function. We prove that there is no permutation of variables that preserves the values of an APN function. Upper bounds for the number of symmetric coordinate Boolean functions in an APN function and its coordinate functions invariant under a cyclic shift are obtained. For n ≤ 6, some upper bounds for the maximal number of identical values of an APN function are given and a lower bound is found for different values of an arbitrary APN function of n variables.     

New generalized almost perfect nonlinear functions

APN (almost perfect non-linear) functions over finite fields of even characteristic are widely studied due to their applications to the design of symmetric ciphers resistant to differential attacks. This notion was recently generalized to GAPN (generalized APN) functions by Kuroda and Tsujie to odd characteristic p. They presented some constructions of GAPN functions, and other constructions were given by Zha et al. We present new constructions of GAPN functions both in the case of monomial and multinomial functions. Our monomial GAPN functions can be viewed as a further generalization of the Gold APN functions. We show that a certain technique used by Hou to construct permutations over finite fields also yields monomial GAPN functions. We also present several new constructions of GAPN functions which are sums of monomial GAPN functions, as well as new GAPN functions of degree p which can be written as the product of two powers of linearized polynomials. For this latter construction we describe some interesting differences between even and odd characteristic and also obtain a classification in certain cases.     

A matrix approach for constructing quadratic APN functions

A one to one correspondence is given between quadratic homogeneous APN functions and a special kind of matrices which we call as QAM’s. By modifying the elements of a known QAM, new quadratic APN functions can be constructed. Based on the nice mathematical structures of the QAM’s, an efficient algorithm for constructing quadratic APN functions is proposed. On \(\mathbb {F}_{2^7}\) , we have found 471 new CCZ-inequivalent quadratic APN functions, which is 20 times more than the number of the previously known ones. Before this paper, It is only found 23 classes of CCZ-inequivalent APN functions on \(\mathbb {F}_{2^8}\) . With the method of this paper, we have found 2,252 new CCZ-inequivalent quadratic APN functions, and this number is still increasing.     

New families of perfect nonlinear polynomial functions

A new class of almost perfect nonlinear (APN) polynomial functions has been recently introduced. We give some generalizations of these functions and deduce new families of perfect nonlinear (PN) functions. We show that these PN functions are CCZ-inequivalent to the known perfect nonlinear functions.     

Relating three nonlinearity parameters of vectorial functions and building APN functions from bent functions

We survey the properties of two parameters introduced by C. Ding and the author for quantifying the balancedness of vectorial functions and of their derivatives. We give new results on the distribution of the values of the first parameter when applied to F + L, where F is a fixed function and L ranges over the set of linear functions: we show an upper bound on the nonlinearity of F by means of these values, we determine then the mean of these values and we show that their maximum is a nonlinearity parameter as well, we prove that the variance of these values is directly related to the second parameter. We briefly recall the known constructions of bent vectorial functions and introduce two new classes obtained with Gregor Leander. We show that bent functions can be used to build APN functions by concatenating the outputs of a bent (n, n/2)-function and of some other (n, n/2)-function. We obtain this way a general infinite class of quadratic APN functions. We show that this class contains the APN trinomials and hexanomials introduced in 2008 by L. Budaghyan and the author, and a class of APN functions introduced, in 2008 also, by Bracken et al.; this gives an explanation of the APNness of these functions and allows generalizing them. We also obtain this way the recently found Edel?CPott cubic function. We exhibit a large number of other sub-classes of APN functions. We eventually design with this same method classes of quadratic and non-quadratic differentially 4-uniform functions.     

On the equivalence of quadratic APN functions

Establishing the CCZ-equivalence of a pair of APN functions is generally quite difficult. In some cases, when seeking to show that a putative new infinite family of APN functions is CCZ inequivalent to an already known family, we rely on computer calculation for small values of n. In this paper we present a method to prove the inequivalence of quadratic APN functions with the Gold functions. Our main result is that a quadratic function is CCZ-equivalent to the APN Gold function x^2r+1{x^{2^r+1}} if and only if it is EA-equivalent to that Gold function. As an application of this result, we prove that a trinomial family of APN functions that exist on finite fields of order 2 ⁿ where n ≡ 2 mod 4 are CCZ inequivalent to the Gold functions. The proof relies on some knowledge of the automorphism group of a code associated with such a function.