高精度模拟函数

在数字水印应用中,利用模拟函数将秘密信息编码为载体特征值,并使特征值在编码与原始载体中的概率分布一致,能提高掩密载体统计上不可检测的性能.采用相对熵作为度量随机变量两种分布距离的指标,设计并证明了具有任意精度的模拟函数计算方法.根据指定精度将特征值变量的概率分布用幂级数扩展,构造前缀码,利用前缀码对秘密信息编码得到模拟结果.数值实验也证实了该算法的有效性.     

两类三元极小码与其完全重量计数器（英文）

最近,极小码因其在秘钥共享和二方计算中的应用被广泛研究.构造反Ashikhmin-Barg界的极小码,然后确定其完全重量计数器是编码与密码中有趣的研究.本文基于指数和与Krawtchouk多项式,利用定义在F₃^m中的向量集函数给出了两类反Ashikhmin-Barg三元极小码,并确定了其完全重量计数器.     

一类二元低重线性码及其重量分布（英文）

线性码在秘密共享方案、认证码、强正则图以及结合方案等领域有广泛应用,已成为编码理论中重要的研究内容.本文利用布尔函数构造了一类二元线性码,并运用Walsh变换完全确定了这类线性码及其对偶码的重量分布.     

最优循环局部修复码的构造

局部修复码是分布式存储编码领域的一个热门研究方向,具有局部性(r,δ)的局部修复码对丢失节点修复具有更高的效率.文章利用限域F_q上循环码构造了两类具有局部性(r,δ),最小距离为d=δ+4,码长n为q+1倍数的最优局部修复码.     

利用有限域上的向量空间构作一种新的A~2-码

利用有限域上的向量空间的子空间作了一个A~2-码,并计算了该码的参数.在假定发方编码规则和收方解码规则按等概率分布选取时,计算了各种攻击成功的概率.     

有限域上一类等维码的下界

等维码凭借其在随机线性网络编码中的良好的差错控制得到广泛研究,对于给定维数和最小距离的等维码所含码字的最大个数目前还没有一般性结果.Tuvi Etzion和Alexander Vardy给出了一定等维码所含码字最大个数的上界和下界,首先利用对偶空间构造等维码C(n,M,2k,k),达到了此类码所含码字的下界,然后具体构造了最优等维码C(7,41,4,2).     

两类子域码的重量分布（英文）

子域码是一类特殊的线性码.线性码由于其有效的编码及译码算法,在电子消费产品、数据存储系统和通信系统中有广泛的应用.然而,确定线性码的重量分布通常是困难的工作.本文给出了两类二元子域码C₍₍H(f)_<sub>1))~((2))和C₍₍H(f)_<sub>2))~((2))及其对偶码的重量分布,其中f₁(x)=x~4,f₂(x)=x~6+x~4+x~2.     

卡氏积码的r-MDR码与P_r-MDS码

本文研究了卡氏积码的r-广义Hamming重量计算公式和广义Singleton界,利用r-卡氏积码的子码仍为卡氏积码,证明了r-MDR码或Pr-MDR码的卡氏积码仍为r-MDR码或Pr-MDR码.同时也给出了这一个结果的部分逆命题.     

纠错编码中的代数理论与方法

纠错编码是保证通信可靠性的重要手段.本文首先介绍了纠错编码的基本概念和主要数学问题,然后基于线性代数、抽象代数的理论与方法,讨论了两类常见的纠错编码——线性码、循环码.     

p-进制码的自对偶码

本文研究了p-进制环Zp∞={∞∑l=0 alpl|0≤al≤p-1}上线性码的自对偶码的问题.利用p-进制环Zp∞上码C在有限链环Zpα的投影码的自正交性与对偶性,得到了p-进制环上码C的自正交性与对偶性的两个结果.     

BILINEAR FORMS AND LINEAR CODES

Abraham Lempel et al^[1] made a connection between linear codes and systems of bilinear forms over finite fields. In this correspondence, a new simple proof of a theorem in [1] is presented; in addition, the encoding process and the decoding procedure of RS codes are simplified via circulant matrices. Finally, the results show that the correspondence between bilinear forms and linear codes is not unique.     

On 2-dimensional insertion-deletion Reed-Solomon codes with optimal asymptotic error-correcting capability

Reed-Solomon codes have gained a lot of interest due to its encoding simplicity, well structuredness and list-decoding capability [6] in the classical setting. This interest also translates to other metric setting, including the insertion and deletion (insdel for short) setting which is used to model synchronization errors caused by positional information loss in communication systems. Such interest is supported by the construction of a deletion correcting algorithm of insdel Reed-Solomon code in [22] which is based on the Guruswami-Sudan decoding algorithm [6]. Nevertheless, there have been few studies [3] on the insdel error-correcting capability of Reed-Solomon codes.In this paper, we discuss a criterion for a 2-dimensional insdel Reed-Solomon codes to have optimal asymptotic error-correcting capabilities, which are up to their respective lengths. Then we provide explicit constructions of 2-dimensional insdel Reed-Solomon codes that satisfy the established criteria. The family of such constructed codes can then be shown to extend the family of codes with asymptotic error-correcting capability reaching their respective lengths provided in [3, Theorem 2] which provide larger error-correcting capability compared to those defined in [25].     

利用有限域GF（2m）上的三项式构造二元循环码

循环码是一类特殊的线性码,由于循环码快速的编码和译码算法,它被广泛应用于消费电子,数据存储以及通信系统当中.在本文中,利用特征是偶数的有限域上的三项式构造出了两类二元循环码,我们不仅可以确定出这两类循环码最小距离的下界,而且这两类循环码在参数的选取上非常的灵活.     

The Theory of Cyclic Codes and a Generalization to Additive Codes

We present a new approach to the theory of cyclic and constacyclic codes and generalize the theory to cover the family of additive (not necessarily linear) cyclic codes. The approach is based on the action of the Galois group (cyclotomic cosets). The conventional representation of cyclic codes as ideals in a factor ring of the polynomial ring is not needed.     

Synchronizing chaotic systems using control based on a special matrix structure and extending to fractional chaotic systems

This work presents a direct approach to design stabilizing controller based on a special matrix structure to synchronize chaotic systems and extends the approach to synchronize fractional chaotic systems. With this method, chaos synchronization is implemented in Lorenz chaotic systems with known parameters and the same to Lorenz chaotic systems with unknown parameters. Especially, fractional Lorenz chaotic system with unknown parameters is synchronized by fractional Chen chaotic system too. Numerical simulations confirm the effectiveness of the method proposed.     

A generalization of quasi-twisted codes: Multi-twisted codes

Cyclic codes and their various generalizations, such as quasi-twisted (QT) codes, have a special place in algebraic coding theory. Among other things, many of the best-known or optimal codes have been obtained from these classes. In this work we introduce a new generalization of QT codes that we call multi-twisted (MT) codes and study some of their basic properties. Presenting several methods of constructing codes in this class and obtaining bounds on the minimum distances, we show that there exist codes with good parameters in this class that cannot be obtained as QT or constacyclic codes. This suggests that considering this larger class in computer searches is promising for constructing codes with better parameters than currently best-known linear codes. Working with this new class of codes motivated us to consider a problem about binomials over finite fields and to discover a result that is interesting in its own right.     

基于混沌理论的创新网络中组织间信任演化研究

以往关于信任的研究是在稳定均衡的假设下进行的,然而信任演化过程中会表现出非线性的混沌状态,具有复杂系统的特征。基于演化博弈理论和混沌理论,建立了创新网络中组织间信任演化模型,分析了创新网络中组织间信任的复杂性、初值敏感性、分岔行为及内随机性等混沌特性,推导出信任演化方程与Logistic映射之间的关系,采用Lyapunov稳定性理论进行混沌性判定,证明创新网络中组织间信任通过倍周期分岔通往混沌,得到了信任从有序进入混沌的一般条件,运用算例进行仿真展示信任演化通往混沌的过程,分析创新网络中信任演化进入混沌区的实际意义,并选择硅谷和筑波科技城两个实例做对比分析,验证了该研究的实用性和有效性。创新网络中组织间信任的混沌演化反映出信任发展的非线性特点,为创新网络中组织间信任的混沌利用和控制提供理论指导。     

A Class of Perfect Ternary Constant-Weight Codes

We construct a class of perfect ternary constant-weight codes of length 2 ^r , weight 2 ^r -1 and minimum distance 3. The codes have codewords. The construction is based on combining cosets of binary Hamming codes. As a special case, for r=2 the construction gives the subcode of the tetracode consisting of its nonzero codewords. By shortening the perfect codes, we get further optimal codes.     

An application of Chen system for secure chaotic communication based on extended Kalman filter and multi-shift cipher algorithm

In recent years chaotic secure communication and chaos synchronization have received ever increasing attention. In this paper a chaotic communication method using extended Kalman filter is presented. The chaotic synchronization is implemented by EKF design in the presence of channel additive noise and processing noise. Encoding chaotic communication is used to achieve a satisfactory, typical secure communication scheme. In the proposed system, a multi-shift cipher algorithm is also used to enhance the security and the key cipher is chosen as one of the chaos states. The key estimate is employed to recover the primary data. To illustrate the effectiveness of the proposed scheme, a numerical example based on Chen dynamical system is presented and the results are compared to two other chaotic systems.     

An improved key agreement protocol based on chaos

Cryptography based on chaos theory has developed fast in the past few years, but most of the researches focus on secret key cryptography. There are few public key encryption algorithms and cryptographic protocols based on chaos, which are also of great importance for network security. We introduce an enhanced key agreement protocol based on Chebyshev chaotic map. Utilizing the semi-group property of Chebyshev polynomials, the proposed key exchange algorithm works like Diffie–Hellman algorithm. The improved protocol overcomes the drawbacks of several previously proposed chaotic key agreement protocols. Both analytical and experimental results show that it is effective and secure.