2个聚合签名方案的密码学分析与改进

分析Zhou-Du方案和Zhao方案,指出这2个基于身份的聚合签名方案是不安全的。在Zhou-Du方案中,单个签名和聚合签名是可伪造的;在Zhao方案中,攻击者可利用单个签名获得签名者的私钥,进而实现任何攻击。对2个方案进行改进,改进的Zhou-Du方案满足不可伪造性,改进的Zhao方案可避免私钥泄露。同时,改进的Zhou-Du方案效率优于原方案,改进的Zhao方案的效率与原方案相同。     

一种混合多变量签名方案

RGB（Red-Green-Blue）方案是一个可以抵抗已知代数攻击的混合多变量签名方案,但是同其他多变量公钥方案一样,它也具有公钥量大的缺点.针对RGB方案这一不足,本文采用循环公钥的思想对RGB方案进行优化,提出了一个新的方案——CyclicRGB混合多变量签名方案.与RGB方案相比较,CyclicRGB方案在降低公钥大小的同时,还具有更快的签名验证.通过本文方案和RGB方案的实验比较,结果表明本文方案的公钥大小约为RGB方案公钥大小的40%,CyclicRGB方案签名验证所需时间为RGB方案签名验证所需时间的60%.     

两个电子货币方案的分析与改进

针对目前电子货币方案在匿名性和公平性等方面的不足,分别使用椭圆曲线和双线性对构造两个电子货币方案,方案在保证顾客匿名性的同时,又可以追踪二次花费的顾客,保证交易的公平进行。首先分析Chaudhry等提出的基于椭圆曲线认证加密的电子货币方案,其方案不能保证消费的匿名性,同时也无法有效解决交易纠纷;接着分析Liu等提出的银行委托离线电子货币方案,发现其方案中用户可以伪造电子货币。然后针对以上方案中的缺陷分别提出了改进后的新方案,并对新方案进行了安全性分析。分析表明,新方案不仅继承了之前方案的安全性和高效性,可以抵抗重放攻击和假冒攻击,还确保了方案的匿名性和公平性。     

一种新的基于离散对数多重签名方案及其分布式计算

该文提出了一种新的基于离散对数多重签名方案 ,该方案改进了基于 Meta- El Gamal方案的多重签名方案和基于 Schnorr方案的多重签名方案中的密钥生成部分 ,成功地避免了原方案中存在的多个签名者如果在生成自己的密钥时相互合作就能达到日后否认消息签名的攻击 .文中最后给出了新方案的一种分布式计算设计 .     

两种无证书签名方案的密码学分析及改进

对苏万力等提出的无证书签名方案和张玉磊等提出的无证书签名方案进行了安全性分析,指出这两个方案在公钥替换攻击下是不安全的,分别给出了这两个方案的一种伪造攻击。提出了这两个方案的改进方案,改进方案克服了原方案的缺陷,提高了系统的安全性,并保留了原方案的优点。     

基于二元Lagrange插值多项式的门限方案

针对基于一元Lagrange插值多项式的门限方案中存在的安全性不足及应用领域受限问题,通过研究现有的门限方案和实数域上的二元Lagrange插值理论,在有限域的基础上,提出一种基于二元Lagrange插值多项式的门限方案。给出了方案的构造及其数值算例,证明了方案的合理性和可行性。将该方案与基于一元Lagrange插值多项式的门限方案进行对比分析,表明新的方案中子秘密丢失所造成的损失更低、合谋难度更大,方案的安全性更高。同时,该方案可以拓宽门限方案的应用领域。     

高效的混合式查找方案*

通过整合基于服务器/客户机模式的集中式查找方案和基于对等计算模式的分散式查找方案,提出了一种混合式查找方案。该方案既有可扩展性、高容错性和自组织性等分散式查找方案的优点,又有利于集中管理和控制,安全性好等集中式查找方案的优势。仿真实验结果表明,该方案的RDP指标优于常规的分散式查找方案,实际查询时间开销更是远远少于常规的分散式查找方案。     

基于双线性对的可验证秘密共享方案

可验证秘密共享是为了解决Shamir的秘密共享方案中庄家诚实性问题和成员诚实性问题.利用双线性对设计了一个知识承诺方案,该承诺方案满足知识承诺的隐藏性和绑定性要求;利用该承诺方案构造了一个秘密共享方案,该方案是可验证的、计算上安全的(t,n)门限方案.     

共享可验证的不可否认门限多代理多重签名方案

Tzeng等人提出了一个共享可验证的不可否认门限多代理多重签名方案（TYH方案）,随后Bao等人与Hsu等人分别指出该方案不能抵抗伪造攻击及不真正具有共享验证的性质,且分别提出了修改方案。基于Tzeng等人方案提出一个新的共享可验证的不可否认门限多代理多重签名方案,与这三个方案相比,该方案效率更高,而且该方案克服了TYH方案的安全性缺陷,具有更好的安全性。     

双CPU系统中应用双端口RAM的争用解决方案

以IDT公司双端口RAM为例，介绍了在双CPU系统中使用双端口RAM时造成争用的原因及三种解决争用的方案：片内硬件判代方案、中断方案和个牌传递方案。第一种是纯硬件方案，不需要软件配合，但CPU应能插入等待周期；后两种方案需要双端口RAM本身硬件的支持及软件的配合。除这三种方案外本文还提出了软件判优方案，并得到成功应用。软件判代方案是纯软件方案，不需要双端口RAM的硬件支持。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.