无碰撞CPK的种子库构建和选取方案

组合公钥CPK(Combined Public Key)是我国拥有完全知识产权的认证技术,与PKI和IBC相比有其独特的优势。但由于密钥由种子密钥经过组合运算生成,因此可能发生碰撞,有效解决碰撞问题已成为CPK体制发展和完善的关键。介绍了CPK的发展、研究现状和存在问题;根据其构建特点,提出了两种新的种子公/私钥组合选取方法,使得在相同规模的安全需求下,所需种子公/私钥量大大减少;针对产生碰撞的两种可能因素提出了解决方案:用分组密码对用户标识进行映射、按照特定规则产生种子公/私钥库以及对椭圆曲线参数进行约束,从根本上消除了碰撞。优化后的CPK体制,无碰撞,种子库规模小,构建效率高,占用空间少,安全性高,可靠性强,便于管理。     

基于椭圆曲线密码系统的组合公钥技术

提出了一种基于椭圆曲线密码系统的组合公钥技术。组合公钥技术将一定数量的私钥因子和公钥因子组成私钥因子矩阵和公钥因子矩阵,并通过映射算法和组合因子矩阵分别计算出用户的公钥和私钥,试图解决大型专用网中大规模密钥管理的难题。     

解决组合公钥共谋攻击和密钥碰撞的新方法

以解决组合公钥体制中共谋攻击和密钥碰撞问题为目的。首先,针对线性共谋攻击,提出了一种新的构造种子矩阵的方法,使得种子密钥和大于基点加法群的阶数,从而使密钥之间不能相互线性表示。其次在密钥的生产过程中,引入系数破坏了层不同和层互斥不同的关系,为解决选择共谋攻击提供了一种有效的方法,同时增强了抵御随机共谋攻击的能力。最后,在密钥产生的流程中,通过公钥对比来避免密钥碰撞,为解决密钥碰撞问题提出了一种新方法。     

基于多线性映射的环签名研究

采用多个密钥生成中心共同作用产生用户私钥的思想,基于多线性映射构造了一个基于ID的环签名方案,使得任何一个不可信的密钥生成中心都无法单独伪造有效的环签名,解决了单个密钥生成中心不可信的问题;并将该方案扩展到一般结构.     

基于组合公钥的用户公钥认证算法

为解决组合公钥算法中的共谋攻击问题及用户私钥托管问题,提出一种基于组合公钥的用户公钥认证算法。其中,密钥管理中心生成用户的签名公私钥矩阵,用户随机生成自己的公私钥对,密钥管理中心使用用户的签名私钥对用户的公钥进行签名。理论分析证明,该算法使用签名私钥矩阵代替单个的签名私钥,从而扩大了签名私钥的空间,增强了系统的安全性。     

无线传感器网络中一种新的混合密钥管理方法

密钥管理作为传感器网络安全中最为基本的环节,在认证和加密过程中起着至关重要的作用。提出了一种新的混合密钥管理方法。该方案借助于Blom矩阵和混沌序列来完成密钥预分配,使得所有的簇头间、节点间以及节点和它的簇头间都能进行安全通信。分析表明：该方法占用较小密钥存储空间,同时支持网络的拓扑结构的变化,能动态地管理密钥信息,从而解决了密钥泄漏等问题。     

一种基于混合混沌序列的图像置乱加密算法

由Logistic映射产生的混沌序列常被用来置乱加密数字图像，但迄今为止，在国内外有关文献中，均未提到由Logistic映射产生的混沌序列中存在“平凡密钥”和“拟平凡密钥”的现象。如果用“平凡密钥”和“拟平凡密钥”作为Logistic映射的初始值，则将无法产生可用于图像置乱的混沌序列，并且在Logistic映射中存在无穷多个“平凡密钥”和“拟平凡密钥”，这可能会导致对图像置乱加密无效，这是值得注意的问题．针对该问题，在对由Logistic映射产生的混沌序列中存在的“平凡密钥”和“拟平凡密钥”进行研究的基础上，提出了一种新的基于混合混沌序列的图像置乱加密算法，从而彻底解决了“平凡密钥”和“拟平凡密钥”对图像置乱加密无效的问题。     

基于身份的组合公钥管理方案

基于椭圆曲线双线性对的特殊性质,设计一种基于身份的组合公钥密钥管理方案。该方案按照组合公钥中用户密钥生成用户公钥,简化了身份到椭圆曲线点群的映射。本方案解决了共谋攻击问题,并且解决了用户私钥安全分发的问题。     

基于标识的组合公钥体制的原理

基于标识的组合公钥体制CPK是我国具有自主知识产权的解决大规模网络环境中密钥生产、分发与证书验证难题的极富创造性的新技术。本文介绍该体制主要内容及其数学原理。第一部分简述椭圆曲线密码的基础知识,并以密钥交换协议为例说明它的应用。第二部分首先介绍组合密钥生成的理论与方法,继而给出CPK的组合密钥生成方式—以一定数量的种子公私钥对构成配对的公开密钥矩阵和私有密钥矩阵,通过标识的映射选取两矩阵对应位置上的多个公开密钥和私有密钥,经计算分别得到多个公开密钥之和与私有密钥之和构成一个组合的公私钥对。第三部分介绍标识映射的计算方法,包括hash函数,行映射算法,列置换算法。     

组合公钥体制的线性共谋攻击分析

针对组合公钥(CPK)体制中的线性共谋攻击问题,从其本质出发,根据密钥产生原理提出了新的方程组构造方法。通过对方程组的系数矩阵进行线性变换,求得了方程组的秩,发现其小于私钥矩阵的种子数;同时,分析了私钥的构造,发现增广矩阵的秩不等于系数矩阵的秩。由此两方面证明了即便攻击者得到所有私钥也无法解得方程组的唯一解。因此,论证了组合公钥体制不存在线性共谋攻击的威胁。     

Random Exploration of the Procedural Space for Single-View 3D Modeling of Buildings

In this paper we tackle the problem of 3D modeling for urban environment using a modular, flexible and powerful approach driven from procedural generation. To this end, typologies of architectures are modeled through shape grammars that consist of a set of derivation rules and a set of shape/dictionary elements. Appearance (from statistical point of view with respect to the individual pixel’s properties) of the dictionary elements is then learned using a set of training images. Image classifiers are trained towards recovering image support with respect to the semantics. Then, given a new image and the corresponding footprint, the modeling problem is formulated as a search of the space of shapes, that can be generated on-the-fly by deriving the grammar on the input axiom. Defining an image-based score function for the produced instances using the trained classifiers, the best rules are selected, making sure that we keep exploring the space by allowing some rules to be randomly selected. New rules are then generated by resampling around the selected rules. At the finest level, these rules define the 3D model of the building. Promising results on complex and varying architectural styles demonstrate the potential of the presented method.     

A novel and effective image encryption algorithm based on chaos and DNA encoding

In this paper, we proposed a novel and effective image encryption algorithm based on Chaos and DNA encoding rules. Piecewise Linear Chaotic Map (PWLCM) and Logistic Map are applied to generate all parameters the presented algorithm needs and DNA encoding technology functions as an auxiliary tool. The proposed algorithm consists of these parts: firstly, use PWLCM to produce a key image, whose pixels are generated by Chaos; Secondly, encode the plain image and the key image with DNA rules by rows respectively and different rows are encoded according to various rules decided by logistic map; After that, employ encoded key image to conduct DNA operations with the encoded plain image row by row to obtain an intermediate image and the specific operation executed every row is chosen by logistic map; Then, decode the intermediate image as the plain image of next step. Finally, repeat steps above by columns again to get the ultimate cipher image. The experiment results and analysis indicate that the proposed algorithm is capable of withstanding typical attacks and has good character of security.     

基于Chen超混沌和DNA的彩色图像加密算法

为了提高图像在传输过程中的安全性,使得用户有更好的体验感,将Chen超混沌系统和DNA编码引入图像加密领域;彩色数字图像根据红、绿、蓝三个通道分为三个二维矩阵,并对三个二维矩阵进行DNA分区域编码处理,增加了编码运算的多样性,使得加密过程更加安全;由Chen超混沌系统生成的序列决定了每个二维矩阵的DNA编码解码规则和运算规则,按照相应规则进行加密,加密后由分段Logistic生成相应的序列再次进行行、列置换,分段的Logistic混沌映射可以让系统更快的进入混沌状态;合并红、绿、蓝三个通道的三个二维矩阵,生成三维矩阵,最终得到相应的彩色加密图像。选取相应的彩色图像进行仿真实验,最终的仿真结果表明,所提出的算法加密效果和相关性能指标良好,同时具有较强的安全性和鲁棒性。     

立方多变量公钥密码体制的最小秩分析

立方加密体制是经典的多变量公钥密码体制Square的改进方案,其中心映射由平方映射改为了立方映射,由此将公钥多项式从二次提升到三次来抵抗针对二次多变量公钥密码体制的最小秩攻击。针对这种体制,提出一种结合差分的最小秩攻击,旨在恢复它的私钥。首先,分析体制的中心映射差分,并根据差分后的结构来确定它的秩;然后,求解公钥差分,并提取二次项的系数矩阵;接着,由系数矩阵以及确定的秩构造一个最小秩问题;最后,结合扩展的Kipnis-Shamir方法对问题进行求解。实验结果表明,利用最小秩攻击可以恢复立方加密体制的私钥。     

A novel image encryption algorithm based on chaotic shuffling method

This article proposes a novel image encryption algorithm based on a chaotic shuffling-diffusion method. First, a chaotic sequence which is generated by a first logistic map is used to label the row coordinate of pixels of the scrambled image. Second, a second logistic map is used to label the column coordinate of pixels of the scrambled image. Then, using our proposed new pixel exchange model to change the position of pixels, we can achieve the effect of scrambling the image. Third, a matrix that is the same size as the plain image is generated by a third logistic map in order to enlarge the key space according to MOD operation and XOR operation by itself. Furthermore, the key sum is related to the plaintext, which makes the encryption system extremely sensitive to resist a chosen-plaintext attack. The simulation results show that this algorithm has properties of big key space, high sensitivity to key, and the ability to resist statistical analysis, differential attacks, plaintext attacks, and chosen-plaintext attacks so that it has higher security and can be suitable for image encryption.     

A robust and lossless DNA encryption scheme for color images

In this paper, a new robust and lossless color image encryption algorithm is presented based on DNA sequence operation and one-way coupled-map lattices (OCML). The plain-image is firstly decomposed into three gray-level components and we randomly convert them into three DNA matrices by the DNA encoding rules. Then the XOR operation is performed on the DNA matrices for two times. Next, the shuffled DNA matrices are transformed into three gray images according to the DNA decoding rules. Finally, a diffusion process is further applied to change the image pixel’s values by a key stream, and the cipher-image is attained. The key stream generated by OCML is related to the plain-image. Experimental results and security analysis demonstrate that the proposed algorithm has a good encryption effect and can withstand various typical attacks. Furthermore, it is robust against some common image processing operations such as noise adding, cropping, JPEG compression etc.

     

Gauss-Markov加密矩阵构造及图像加密应用

为了解决加密矩阵难以构造的问题,提出一种获得整数矩阵的新算法,利用Gauss-Markov过程生成一个随机序列,将该序列转换为一系列的低阶整数矩阵,从中寻找行列式等于l的整数矩阵,并对这些矩阵进行张量积运算得到高阶加密矩阵,应用于数字图像加密.加密实例和理论分析及对比表明,该算法可自动生成安全性很高的加密矩阵,且加密结果具有良好的随机特性和自相关性,能满足密码学的要求.     

Color image encryption based on DNA encoding and pair coupled chaotic maps

Information security has become a significant issue in encryption due to the rapid progress of internet and network. Therefore, the development of the encryption algorithm is a growing and significant problem. In this study, a new color image encryption was introduced based on DNA complementary rules and pair coupled chaotic maps. At first, the plain color image was divided into three components (R, G, B) being converted into three DNA matrices using DNA encoding rules. Secondly, DNA addition for R, G and B components was implemented and scrambled the elements position of three DNA sequence via the pair coupled chaotic maps. Three gray coded images obtained and RGB encrypted image was achieved by restructuring R, G, B components. The simulation of experimental result and security analysis showed that this algorithm had larger secret key space and strong secret key sensitivity and it had excellent ability to resist against statistical and differential attacks.

     

An Availability Model for Distributed Transaction Systems

A method is proposed for quantitatively evaluating the availability of a distributed transaction system (DTS). The DTS dynamics can be modeled as a Markov process. The problem of formulating the set of linear homogeneous equations is considered, obtaining the related coefficient matrix, that is, the transition rate matrices of the DTS elements. Such operations can be performed according to the rules of Kronecker algebra. The transition rate matrices are used to calculate the probabilities of the different possible states of the DTS. The availability with respect to a transaction T is computed through its representation by means of a structure graph and a structure vector related to the probabilistic state of the DTS element relevant to the transaction T itself.     

基于混沌序列的通用数字图像加密算法

为有效保护数字图像的信息,提出一种基于混沌序列的通用的数字图像加密算法。先根据密钥及图像大小产生一个混沌序列,然后根据子密钥及图像类型将其转换为无符号整数序列,最后再依次与对应的像素值进行异或运算以实现置换加密。应用评价指标对加密效果与安全性进行分析。理论分析与实验结果表明,该算法密钥空间大,具有良好的加密效果、安全性与统计特性,且抗干忧能力较强。