椭圆曲线密码的安全性分析

椭圆曲线密码的数学基础是椭圆曲线离散对数问题（ECDLP）。除了一些极特殊的椭圆曲线，求解ECDLP的算法都为安全指数时间，其中目前最好的算法是并行Pollard‘s rho算法，文章给出了用该算法求解ECDLP的一个实例。     

ECC2-131的并行Pollard rho算法实现分析

Pollard rho算法与其分布式版本算法是目前求解有限域上椭圆曲线群的离散对数问题被公认的最优算法.自该算法提出以来,许多密码学家提出了多种分布式Pollard rho算法的改进算法.本文对基于不同迭代函数的三种的分布式Pollard rho算法的效率进行分析,并针对ECC2-131在通用CPU上对算法进行软件程序的实现.本文发现基于r-加游走的算法在理论分析和程序实现上都有着最优的效率,说明基于r-加游走的分布式Pollard rho算法在求解ECDLP上仍占有很大优势.本文给出在计算机工作站和天河二号超级计算机上测量得出的Pollard rho算法的效率,发现在当前求解离散对数问题的算法和计算机的计算能力上求解ECC2-131仍然是困难的,在时间和金钱上的开销不符合实际.本文还找出有限域F2131上运算性能最优的不可约多项式.通过域的同构诱导出椭圆曲线的同构, ECDLP能在同构后得到的椭圆曲线上进行求解.若算法的软件实现使用同构后得到的椭圆曲线,则有限域模运算有11.29%的效率提升,乘法运算有11.23%的效率提升.通过有限域运算效率的提升可以进一步提高求解ECDLP的效率...     

基于椭圆曲线的门限多重秘密共享方案

本文基于椭圆曲线密码系统,即椭圆曲线离散对数问题（ECDLP）的难解性,提出了一个安全性更强的门限多重秘密共享方案.该方案具有以下特点：相对于传统的基于大数分解和离散对数体制,在子秘密长度及安全性等方面更具优势;无需更改参与者的子秘密实现任意多个秘密共享;提供了验证机制防止秘密分发者欺诈以及参与者之间的相互欺诈,避免了以往很多方案中交互信息量大,秘密分发者计算量大的缺点.     

曙光5000A高效能计算节点的设计与实现

由于求解问题和系统规模的不断扩大,基于cluster架构的高性能计算机面临扩展性、可靠性、功耗、占地面积、均衡性等诸多挑战。该文针对计算模块、交换管理模块、自适应功率管理、专用FPGA硬件加速部件、高速PCI-E全交换扩展等方面,设计并实现高效能计算节点。基于该节点构建的曙光5000A百万亿次计算机能有效解决计算密度、I／O扩展及带宽瓶颈和能耗等方面的瓶颈。     

目标径向速度求解方法的研究

针对某些条件下目标径向速度无法直接测量的问题,讨论了如何利用雷达和GPS测量系统的测量数据间接求解目标径向速度。首先对雷达和GPS测量系统给出了一种基于距离一阶差分近似求解径向速度的方法,具有易于操作的优点,但在采样间隔较大时测量精度下降严重。接着,根据内积公式对GPS测量系统给出了一种与采样间隔无关的基于速度矢量求解径向速度的方法。该方法求解公式简洁、计算步骤简单、易于理解,解决了如何间接求指定点位的目标的径向速度的问题,具有一定的应用价值。     

基于ECC的定期更新的可验证秘密共享方案

本文提出了一个基于椭圆曲线密码体制（ECC）的、定期更新的可验证的秘密共享方案.该方案具有子秘密定期更新、子秘密可验证和可防欺诈的特点.方案的安全性基于求解有限域上椭圆曲线离散对数问题（ECDLP）的难解性.     

一种基于动态规划策略的离散动态大系统递阶优化神经网络

给出了一种具有集成化特征的、快速求解大规模系统动态规划问题的神经网络模型(LDPNN),该神经网络将大系统的各子系统的动态方程约束嵌入局部优化子网络,使得整个网络的结构简洁、紧凑,便于硬件实现,该神经网络计算模型克服了数值方法迭代计算的缺陷,求解效率高,适宜于大规模动态系统实时优化应用.     

基于生物计算的分布式计算系统

分布式计算技术提供了充分利用现有网络资源的有效途径。该文论述了基于解决生物计算中难解问题的具有开放接口的分布式并行计算系统的设计与实现技术。系统兼有开放式、异构性、容错性与易用性等特点。讨论了系统的容错性机制、检查点策略及任务调度算法。对Motif Finding问题的求解验证表明,分布式并行计算机制能大大缩短问题的求解时间,为计算领域的难解问题提供有效的解决途径。     

一种基于扩展规则的#SAT 求解系统

#SAT 问题是SAT 问题的扩展,需要计算出给定命题公式集合的模型个数.通过将问题求解沿着归结的反方向进行,并利用容斥原理解决由此带来的空间复杂性问题,提出了一种基于扩展规则的模型计数和加权模型计数问题求解框架,可以看作是目前所有模型计数问题求解方法的一种补方法.证明了该方法的完备性和有效性,设计了基于扩展规则的#SAT 求解系统:JLU-ERWMC.实验结果表明,JLU-ERWMC 在有些问题中优于目前最为高效的#SAT 问题求解系统.     

基于多Agent的动态数据并行计算方法研究

为实现动态数据的快速处理和计算,提出一种基于多Agent和分布式并行计算的动态数据处理方法。该方法以智能Agent作为计算和控制的最小单元,构建有向无环的动态网络拓扑结构,采用基于信任度的合同网模型,并与阈值相结合,实现动态数据处理和快速求解,体现系统的智能性和实时性。实验结果表明,该计算方式与传统计算方式相比,系统的计算速率显著提高,实现了动态数据的实时性处理。     

-一种安全的椭圆曲线多重数字签名方案

现有的椭圆曲线数字签名方案ECDSA不适合进行多重数字签名，文章对ECDSA方案稍作了改进，给出一种安全性建立在椭圆曲线离散对数难题（ECDLP）上的、适合多重数字签名的椭圆曲线数字签名方案，然后在此基础上提出一种安全性建立在ECDLP上的多重数字签名方案，分析表明这两种方案都正确并且能够有效抵抗攻击。     

Computing Prime Factorization And Discrete Logarithms: From Index Calculus To Xedni Calculus

The integer factorization problem (IFP), the finite field discrete logarithm problem (DLP) and the elliptic curve discrete logarithm problem (ECDLP) are essentially the only three mathematical problems that the practical public-key cryptographic systems are based on. For example, the most famous RSA cryptosystem is based on IFP, the US government's Digital Signature Standard, DSS, is based on DLP, whereas the ECC (Elliptic Curve Cryptography) and Elliptic Curve Digital Signature Algorithm (ECDSA) are based on ECDLP. The security of such cryptographic systems relies on the computational intractability of these three mathematical problems. In this paper, we shall present a survey of various methods for solving the IFP/DLP and particularly the ECDLP problems. More specifically, we shall first discuss how the index calculus as well as quantum algorithms can be used to solve IFP/DLP. Then we shall show why the index calculus cannot be used to solve ECDLP. Finally, we shall introduce a new method, xedni calculus , due to Joseph Silverman, for attack ECDLP; some open problems and new research directions, will also be addressed.     

The distributed program reliability analysis on ring-type topologies

Distributed computing system (DCS) has become very popular for its high fault-tolerance, potential for parallel processing, and better reliability performance. One of the important issues in the design of the DCS is the reliability performance. Distributed program reliability (DPR) is addressed to obtain this reliability measure. In this paper, we propose a polynomial-time algorithm for computing the DPR of ring topology and show that solving the DPR problem on a ring of trees topology is NP-hard.Scope and purposeThe widespread use of distributed computing system is due to the price–performance revolution in microelectronics, the development of cost-effective and efficient communication subsets, the development of resource sharing software, and the increased user demands for communication, economical sharing of resources, and productivity. This article is concerned with the analysis of distributed program reliability on a ring-distributed computing system. The distributed program reliability is a useful measure for reliability evaluation of distributed computing system. The distributed program reliability analyses also give a good index for designing a high-reliability-performance-distributed computing system.     

基于最大粒的规则获取算法

粒计算是模拟人类思维和解决复杂问题的方法,它是复杂问题求解、海量数据挖掘、模糊信息处理的有效工具。文中首先分析并指出传统的规则获取方法存在的某些弊端,并从粒计算的角度分析属性约简的粒度原理,指出属性约简过程的本质是寻找决策划分空间的一个极大近似划分空间,而在极大近似划分空间上提取的规则可能不是最简规则。为此,提出一种基于最大粒的规则获取算法,该算法根据条件属性对论域形成的分层递阶的划分空间,自顶向下逐渐提取最大粒对应的规则。仿真实验表明该算法提高粗糙集的泛化能力。     

基于椭圆曲线的限制性群盲签名方案

基于椭圆曲线离散对数问题,将限制性群盲签名和知识签名的思想推广到椭圆曲线循环群上,提出了一种新的限制性群盲签名方案,以提高其安全性和效率。并以此为基础设计了一种多银行电子现金系统。分析表明,方案是安全的、高效的。     

A conservative flux for the continuous Galerkin method based on discontinuous enrichment

Abstract In this paper we develop techniques for computing elementwise conservative approximations of the flux on element boundaries for the continuous Galerkin method. The technique is based on computing a correction of the average normal flux on an edge or face. The correction is a jump in a piecewise constant or linear function. We derive a basic algorithm which is based on solving a global system of equations and a parallel algorithm based on solving local problems on stars. The methods work on meshes with different element types and hanging nodes. We prove existence, uniqueness, and optimal order error estimates. Lastly, we illustrate our results by a few numerical examples.     

Distributed and asynchronous solver for large CPU intensive problems

Solving large-scale scientific problems represents a challenging and large area in numerical optimisation. Devoted techniques may improve the results achieved for these problems. We aimed to design an specific optimisation technique for these problems. In this case, a new swarm-based algorithm based on bees foraging behaviour is presented. This system must rely on large computing infrastructures that present specific characteristics. We designed this algorithm for being executed on the grid. The resulting algorithm improves the results obtained for the large-scale problem described in the paper by other algorithms. It also delivers an optimal usage of the computational resources. This work represents one of the few evidences for solving real large-scale scientific problems with a devoted algorithm using large and complex computing infrastructures. We show the capabilities of this approach when solving these problems.     

Design and implementation of an adaptive job allocation strategy for heterogeneous multi‐cluster computing systems

Cluster computing is an attractive approach to provide high‐performance computing for solving large‐scale applications. Owing to the advances in processor and networking technology, expanding clusters have resulted in the system heterogeneity; thus, it is crucial to dispatch jobs to heterogeneous computing resources for better resource utilization. In this paper, we propose a new job allocation system for heterogeneous multi‐cluster environments named the Adaptive Job Allocation Strategy (AJAS), in which a self‐scheduling scheme is applied in the scheduler to dispatch jobs to the most appropriate computing resources. Our strategy focuses on increasing resource utility by dispatching jobs to computing nodes with similar performance capacities. By doing so, execution times among all nodes can be equalized. The experimental results show that AJAS can improve the system performance. Copyright © 2011 John Wiley & Sons, Ltd.