5元1-弹性函数的代数免疫阶

首先给出了最优代数免疫布尔函数弹性阶的一个上界,并且证明了一类5元1阶弹性函数不是最优代数免疫函数,得到了最优代数免疫函数具有一阶弹性时可能的结构形式;在此基础上,给出了布尔函数代数免疫阶和弹性阶随着变元个数变化的一些结果,最后给出了一个5元1阶弹性的最优代数免疫布尔函数。     

利用特征矩阵构造Bent函数

本文首先研究了Bent函数特征矩阵的性质,并给出了Bent函数的一个等价判别条件。从而引出了Bent函数的一种新的构造方法:由一个已知的n(n≥2)元Bent函数的特征矩阵来构造n+2元Bent函数的特征矩阵。为Bent函数的构造和计数提供了一种新思路.     

广义向量Bent函数

该文完善并拓展了Nyberg(1991)的关于广义向量Bent函数性质的结论,相应于Nyberg给出的正则广义向量Bent函数,提出了负则的广义向量Bent函数的概念:得到有偶数个输入的负则的广义向量Bent函数输出维数也不大于输入维数的一半;证明了奇数个输入的正则和负则的广义向量Bent函数都不存在,这些结果的给出,可使密码设计者避免一味去寻找某类不存在的函数.该文还给出了广义向量Bent函数的一种递归构造法.     

k阶拟Bent函数在密码设计和通信中的应用

王育民、何大可提出了布尔函数关于线性函数的r阶相关度E(r)的概念来刻划布尔函数抵抗相关攻击的能力，本文以极小化所有非零相关度E(r)为主要目的，利用k阶拟Bent函数的特殊性质，给出了一类基于k阶拟Bent函数的“最佳”非线性组合设计的实现，构造了一类平衡的，具有高阶相关免疫性，而且非零相关度一致地小的非退化的布尔函数，并比较了它与基于部分Bent函数的“最佳”非线性组合设计的优劣。最后我们又利用k阶拟Bent函数构造了一类Bent互补函数族和Bent侣，Bent互补函数族和Bent侣在最佳信号设计方面意义重大，这也表明k阶拟Bent函数在密码设计和通信领域都有比较广的应用前景。     

密码学中3类具有特殊Walsh谱值布尔函数的关系

从函数结构角度对Bent函数与Plateaued函数、部分Bent函数与Plateaued函数的关系进行了研究,指出了任意一个Bent函数都可拆分成2个Plateaued函数的链接,而Plateaued函数在满足一定条件下也可拆分成Bent函数的链接.给出了阶n-1Plateaued函数具有非零线性结构时与Bent函数的特殊关系,讨论了部分Bent函数可表示成2个Plateaued函数链接时的条件.研究结果进一步说明了这3类具有特殊Walsh谱值密码函数之间有着紧密的内在联系,为密码设计中使用此类函数提供了重要依据.     

多维超Bent函数的构造

有限域Fp2m上的超Bent函数是与Fp上所有m序列的距离都达到最大的函数,该文研究了F22m 上超Bent函数与GF2m(2)上Bent函数之间的关系,对一类超Bent函数的性质作了深入细致的刻画,给出了有限域Fp2m上多维超Bent函数的两种构造方法．     

均衡弹性函数的结构与弹性阶

弹性函数是相关免疫布尔函数的自然推广。本文讨论均衡弹性函数,得到以下结果:给出了均衡弹性函数的一种结构,并因此得到了由均衡(n,m,2t)弹性函数构造均衡(n+1,m,2t+1)弹性函数的非线性方法;证明了均衡线性函数的弹性阶等于对应线性分组码的码字最小重最减1,且弹性阶上确界常常能由非线性函数所达到。     

关于Bent函数的构造与分类

本文提出了一种构造Bent函数的新方法,依此可定出大量在实用中很重要的Bent函数;本文还对2次Bent函数进行仿射分类,证明了2次Bent函数仅有2类,并定出了其每一类中的代表函数;最后,本文研究了Bent函数的一阶广义相关免疫性。     

代数次数为2的Bent函数的性质及其应用

本文证明了任意代数次数为2的n元Bent函数都与形式为x₁x₂+x₃x₄+…+x_n-1x_n的Bent函数线性等价;给出了以任意已知代数次数为2的n元Bent函数为分量的多维Bent函数的构造法;利用本文所给的方法,对任一主对角线上元素全为0的n阶可逆对称矩阵M₁,都可以构造k-1个主对角线上元素全为0的n阶可逆对称矩阵M₂…,M_k,使得M₁,M₂…,M_k的任意非零线性组合仍是主对角线上元素全为0的阶可逆对称矩阵.     

一类部分Bent函数的判定与构造

本文给出了具有线性结构布尔函数的Walsh谱值的计算公式,证明了布尔函数的非零谱值的个数与线性结构的个数之积不大于2~n,得到了Walsh谱值为⊥2~n,0的2n-1元布尔函数是否是部分Bent函数的判定定理,最后给出了这类部分Bent函数的一个构造方法。     

Krawtchouk polynomials and universal bounds for codes and designsin Hamming spaces

Universal bounds for the cardinality of codes in the Hamming space F_rⁿ with a given minimum distance d and/or dual distance d' are stated. A self-contained proof of optimality of these bounds in the framework of the linear programming method is given. The necessary and sufficient conditions for attainability of the bounds are found. The parameters of codes satisfying these conditions are presented in a table. A new upper bound for the minimum distance of self-dual codes and a new lower bound for the crosscorrelation of half-linear codes are obtained     

Constructions of rotation symmetric 2-resilient functions with 4t-1 number of variables

Some properties of rotation symmetric orbits were proposed in n dimensional vector space over finite field of characteristic 2,a matrix on the distributions of number pairs such as 00,01 and 11 was defined,and a new characterization of 2-resilient rotation symmetric functions was introduced.Constructions of rotation symmetric 2-resilient Boolean functions with 4t-1 number of variables were presented by modifying the support of the linear rotation symmetric functions,such as f₀(x)=x₁+x₂+…+x_n,where n=4t-1.At last,an example was demonstrated to introduce the spirit of the proposed method to construct 2-resilient rotation symmetric functions with 4t-1 number of variables.     

On the minimum distance of ternary cyclic codes

There are many ways to find lower bounds for the minimum distance of a cyclic code, based on investigation of the defining set. Some new theorems are derived. These and earlier techniques are applied to find lower bounds for the minimum distance of ternary cyclic codes. Furthermore, the exact minimum distance of ternary cyclic codes of length less than 40 is computed numerically. A table is given containing all ternary cyclic codes of length less than 40 and having a minimum distance exceeding the BCH bound. It seems that almost all lower bounds are equal to the minimum distance. Especially shifting, which is also done by computer, seems to be very powerful. For length 40⩽n⩽50, only lower bounds are computed. In many cases (derived theoretically), however, these lower bounds are equal to the minimum distance     

Distance-spectrum formulas on the largest minimum distance of blockcodes

A general formula for the asymptotic largest minimum distance (in block length) of deterministic block codes under generalized distance functions (not necessarily additive, symmetric, and bounded) is presented. As revealed in the formula, the largest minimum distance can be fully determined by the ultimate statistical characteristics of the normalized distance function evaluated under a properly chosen random-code generating distribution. Interestingly, the new formula has an analogous form to the general information-spectrum expressions of the channel capacity and the optimistic channel capacity, respectively derived by Verdu and Han (1994) and Chen and Alajaji (1998, 1999). As a result, a minor class of distance functions for which the largest minimum distance can be derived is characterized. A general Varshamov-Gilbert lower bound is next addressed. Some discussions on the tightness of the general Varshamov-Gilbert bound are also provided. Finally, lower bounds on the largest minimum distances for several specific block coding schemes are rederived in terms of the new formulas, followed by comparisons with the known results devoted to the same codes     

A new lower bound for the minimum distance of a cyclic code

A new lower bound for the minimum distance of a linear code is derived. When applied to cyclic codes both the Bose-Chaudhuri-Hocquenghem (BCH) bound and the Hartmann-Tzeng (HT) bound are obtained as corollaries. Examples for which the new bound is superior to these two bounds, as well as to the Carlitz-Uchiyama bound, are given.     

关于q元Alternant码的最小距离

本文给出了ｑ元Ａｌｔｅｒｎａｎｔ码的最小距离一个新的下界，改进了以往有关结果。此外，本文将指出，文献［１］关于Ａｌｔｅｒｎａｎｔ码的最小距离的结果，一般是不成立的。     

Boolean函数的一种构造方法

介绍了一种从完全非平衡函数构造Boolean函数的方法,并说明此构造能够得到Bent函数．