基于多用户双锁加密系统的密钥分存方案

对灰色加密理论中的多用户双锁加密系统进行了改进,提出了一种基于多用户双锁加密系统的密钥分存方案.该方案通过改变灰色微分方程x(0)(k) az(1)(k)=b中z(1)(k)的生成系数(权数),解决了密钥分存中密钥的更新和复用问题,并通过引入一简单的离散对数函数来抵御成员欺骗.     

一种实现一般电路的密钥策略的属性加密方案

属性加密方案中引入访问结构,实现了用户对密文的细粒度的访问控制.任意访问结构都可通过一般电路来实现,因此,设计实现一般电路访问结构的属性加密方案是该领域的研究热点和难点.Garg等基于多线性映射首次提出了实现一般电路访问结构的属性加密方案,但该方案支持的电路是受限的,电路结点只能逐层输出,系统中实现的访问结构的电路深度都是固定值l.为了解决电路受限的问题,本文提出了一种实现一般电路的密钥策略的属性加密方案.在私钥生成算法中,通过对电路进行等价转换,引入转换密钥,实现了任意深度大于1,小于等于l的电路访问结构;将电路中非叶子节点的密钥与该节点的两个输入节点的深度相关,实现了节点的跨层输入.本文基于k-多线性判定性Diffie-Hellman（K-MDDH）假设证明了该方案具有选择安全性.     

基于密文策略属性加密体制的匿名云存储隐私保护方案

针对云存储中数据机密性问题,为解决密钥泄漏与属性撤销问题,从数据的机密性存储以及访问的不可区分性两个方面设计了基于密文策略属性加密体制(CP_ABE)的匿名云存储隐私保护方案。提出了关于密钥泄漏的前向安全的不可逆密钥更新算法;在层次化用户组以及改进的Subset-Difference算法基础上,利用云端数据重加密算法实现属性的细粒度撤销;基于同态加密算法实现k匿名l多样性数据请求,隐藏用户潜在兴趣,并在数据应答中插入数据的二次加密,满足关于密钥泄漏的后向安全。在标准安全模型下,基于l阶双线性Diffie-Hellman(判定性l-BDHE)假设给出所提出方案的选择性安全证明,并分别从计算开销、密钥长度以及安全性等方面验证了方案的性能优势。     

基于素数幂次阶分圆多项式环的多密钥全同态方案

传统的全同态加密方案允许对单个用户的密文进行任意计算,计算结果解密后能够得到与明文计算相一致的结果。多密钥全同态加密方案允许云服务器对多个用户的密文进行任意计算,更适用云计算的应用场景。基于公钥加密方案NTRU的多密钥全同态加密方案被称为NTRU型多密钥全同态加密方案,具有密钥和密文尺寸短、运算速度快和潜在的抗量子攻击等特性。但是,现有的NTRU型多密钥全同态加密方案存在可选的环结构少、使用的环结构容易受到子域攻击等问题。文章以NTRU型多密钥全同态加密方案LTV12为研究对象,将该方案中的2的幂次阶分圆多项式环替换为素数幂次阶分圆多项式环,密钥生成算法采用正则嵌入下的高斯分布,优化了LTV12方案,增加了可选环结构的数量,并使其免受子域攻击的危害,对其实用性和安全性具有推动意义。     

条件型非对称跨加密系统的代理重加密方案

为了减轻云应用中移动设备解密的负担,利用基于身份的广播加密（IBBE）、基于身份的加密（IBE）、基于身份的条件型广播代理重加密方案,提出了多条件型非对称跨加密系统的代理重加密方案。该方案允许发送方将信息加密成IBBE密文,一次性发送给多个接收方,其中任一接收方又可以授权给代理者一个多条件型的重加密密钥,代理者利用该多条件型重加密密钥,能将符合多个条件的原始密文重加密成一个新的接收方可以解密的IBE密文。该方案实现了从IBBE加密系统到IBE加密系统的非对称代理重加密,而且代理者可以根据条件将最初的原始密文进行重加密,避免了不需要进行重加密的原始密文被代理者重加密,提高了代理者重加密的效率,同时节约了接收方获悉正确明文的时间。     

基于多值逻辑阵列变换的数据加密与解密系统研究

本文提出一种基于任一逻辑基值的多值阵列数据加密与解密系统,研究表明:对应于一个k级的规模为m×n的M(≥2)值加密阵列,其密钥空间为M~(k×m×n),因此这种加密系统具有较高的安全性。     

基于双重二维混沌映射的压缩图像加密方案

为了提高混沌加密系统的安全性和加密速度,提出了一种联合混沌映射的轻量级压缩图像加密方案。首先,为了加速加密过程,破坏像素间的相关性,将数字图像分割为图像块,并通过在频域中的处理对其进行压缩;然后,实施2D Logistic混沌映射,用于在密钥生成、置乱和替换阶段对图像像素进重排和换位。此外,为了进一步提高安全等级,在扩散阶段利用另一种混沌映射2D Henon映射来改变置乱图像的像素值。性能评估结果表明,所提方案能够满足图像加密的安全性要求,且密钥空间大。与其他优秀方案相比,该方案能够更好地抵御统计和差分等攻击,且对生成的密钥空间改变具有高度敏感性。其中,密钥空间大小为256位,实现了约99%的NPCR值和超过15%的UACI值。     

基于FPGA的16位数据路径的AES IP核

提出一种基于FPGA的16位数据路径的高级加密标准AES IP核设计方案。该方案采用有限状态机实现,支持密钥扩展、加密和解密。密钥扩展采用非并行密钥扩展,减少了硬件资源的占用。该方案在Cyclone II FPGA芯片EP2C35F484上实现,占用20 070个逻辑单元（少于60%的资源）,系统最高时钟达到100 MHz。与传统的128位数据路径设计相比,更方便与处理器进行接口。     

一个安全有效的概率公钥密码系统

本文提出了一个新的概率公钥密码系统.该系统是多项式安全的,而且,其效率很高,数据膨胀率为1+(k-1)/l,其中k是安全参数,l是被加密数据的长度.     

高效的无线传感器网络交叉加密认证方案

为了解决无线传感器网络中所传数据的机密性和完整性问题,本文提出一种高效的无线传感器交叉加密认证方案。该方案基于对称密钥密码系统,网络中的节点只和其2跳以内的节点共享密钥,传输中的密文始终只加密2层,从而降低存储密钥的空间,减少加、解密时的计算量。此外,方案在加密时引入带投票技术的认证功能,从而在保证数据机密性和完整性的同时大大降低消息丢失的概率。     

Robust solutions of perturbed linear equations

A perturbed system of linear equalitieslangle a_{i},x rangle = b_{i}, i = 1,2,...,n;a_{i} inA_{i};b_{i},inB_{i};xinX(the sets Aiand the intervals Biprescribed a priori) is said to be robust if a solution vectorx_{0}inXcan be found resulting inlangle a_{i},x_{0}rangle in B_{i}for alla_{i} inA_{i}and alli = 1, 2,...,n. A numerical "test for robustness" is developed. This test is seen to involve 2n parameters at most-even when the solution setXis an infinite-dimensional vector space.     

Some Indices of Alphabet Overlap Graph

The undirected de Bruijn graph is often used as the model of communication network for its useful properties,such as short diameter,small maximum vertex degree.In this paper,we consider the alphabet overlap graph G(k,d,s): the vertex set V = {v|v = (v1 ...vk);vi ∈ {1,2,...,d},i = 1,2,...,k};they are distinct and two vertices u = (u1 ...uk) and v = (v1 ...vk) are adjacent if and only if us+i = vi or vs+i = ui (i = 1,2,...,k s).In particular,when s = 1,G(k,d,s) is just an undirected de Bruijn graph.First,we give a formula to calculate the vertex degree of G(k,d,s).Then,we use the corollary of Menger’s theorem to prove that the connectivity of G(k,d,s) is 2ds 2d2s k for s k/2.     

A homotopy method for eigenvalue assignment using decentralized state feedback

This paper addresses the following problem. Given an interconnected systemMcomposed ofNsubsystems of the formA_{i} + B_{i}K_{i},i = 1,..., N , (A_{i}, B_{i}), a controllable pair, and where the off diagonal blocks ofMlie in the image of the appropriate Bi, then is it possible to arbitrarily assign the characteristic polynomial ofMby a suitable selection of the characteristic polynomials ofA_{i} + B_{i}K_{i}? Moreover, is it possible to compute the appropriate characteristic polynomials of theA_{i} + B_{i}K_{i}(or equivalently construct the Ki) needed to do so? The first question is answered by constructing a mappingF: R^{n} rightarrow R^{n}which maps a prescribed set ofnof the feedback gains (elements ofK_{i}, i=1,...,N) to thencoefficients of the characteristic polynomial ofM. The question then becomes, given ap in R^{n}, doesF(x) = phave a solution? The answer is found by constructing a homotopyH: R^{n}x[O.1] rightarrow R^{n}whereH(x,1)= F(x)andH(x,0)is some "trivial" function. Degree theory is then applied to guarantee that there exists anx(t)such thatH(x(t), t) = pfor alltin [0,1]. The parameterized Sard's theorem is then utilized to prove that (with probability 1)x(t)is a "smooth" curve, and hence can be followed numerically fromx(0)tox(1)by the solution of a differential equation (Davidenko's method).     

A minimum principle for a class of discrete-time stochastic systems

A minimum principle is obtained for discrete-time stochastic systems described by the stochastic difference equationx_{k+1} = A_{k}x_{k} + phi_{k}(u_{k})+w_{k}where{w_{k}, k = 0, ... ,N - }is la sequence of independent random vector variables. The control action ukis constrained to belong to a compact set Uk, and the setphi_{k}(U_{k}), k = 0,..., N - 1is convex. The system is open-loop.     

A note on double lacunary statistical $$\sigma$$-convergence of fuzzy numbers

Quite recently, Sava? (Appl Math Lett 21:134–141, 2008), defined the lacunary statistical analogue for double sequence \(X=\{X_{k,l}\}\) of fuzzy numbers as follows: a double sequence \(X=\{X_{k,l}\}\) is said to be lacunary P-statistically convergent to \(X_{0}\) provided that for each \(\epsilon >0\)

$ P-\lim_{r,s}\frac{1}{h_{r,s}}\left | \{(k,l)\in I_{r,s}: d(X_{k,l },X_0)\geq \epsilon\}\right|= 0. $

In this paper we introduce and study double lacunary \(\sigma\)-statistical convergence for sequence of fuzzy numbers and also we get some inclusion theorems.

     

Finite state stochastic games: Existence theorems and computational procedures

Let{X_{n}}be a Markov process with finite state space and transition probabilitiesp_{ij}(u_{i}, v_{i})depending on uiandv_{i}.State 0 is the capture state (where the game ends;p_{oi} equiv delta_{oi});u = {u_{i}}andv = {v_{i}}are the pursuer and evader strategies, respectively, and are to be chosen so that capture is advanced or delayed and the costC_{i^{u,v}} = E[Sum_{0}^{infty} k (u(X_{n}), v(X_{n}), X_{n}) | X_{0} = i]is minimaxed (or maximined), wherek(alpha, beta, 0) equiv 0. The existence of a saddle point and optimal strategy pair or e-optimal strategy pair is considered under several conditions. Recursive schemes for computing the optimal or ε-optimal pairs are given.     

Optimal control of service in tandem queues

Customers arrive in a Poisson stream into a network consisting of twoM/M/1service stations in tandem. The service rateu in [0, a]at station 1 is to be selected as a function of the state (x_{1}, x_{2}) where xiis the number of customers at stationiso as to minimize the expected total discounted or average cost corresponding to the instantaneous costc_{1}x_{1} + c_{2}x_{2}. The optimal policy is of the formu=aoru=0according asx_{1} < S(x_{2}) or x_{1} geq S(X_{2})andSis a switching function. For the case of discounted cost, the optimal process can be nonergodic, but it is ergodic for the case of average cost.     

Stabilizability of the systemẋ(t)=Fx(t)+Gu(t-h)

Stabilizability problem for the systemdot{x}(t)= Fx(t) + Gu(t - h)is considered. For appropriate discrete modelx_{k+1} = Ax_{k} + Bu_{k-1}the feedback controller which has the formu_{k} =Sigmamin{i=0}max{l}F_{i}x_{k-i}is proposed. It is proven that controllability of the pair (A,B) and cyclicity of theAmatrix imply stabilizability. Some extensions and applications are also mentioned.     

Exact control of a system of diffusion equations

It is shown how a vector control function f(x,t) = (f_i(x,t)) can be found that will drive the solution of the linear diffusion system from an arbitrary initial condition u(x,0) = φ(x) = (φ_i(x), i = 1,2,...,n, to an arbitrary final condition u(x,T) = ψ(x) = (ψ_i(x)), i = 1,2,...,n, in arbitrary time T.