基于无证书的盲签密方案

在传统数字签名机制中,用户的公钥需要由经过可信第三方（TTP）签名的证书来保证其可靠性,而Sham ir的基于身份的签名机制尽管不再需要证书,但用户的私钥将无法避免地被TTP所托管。结合无证书公钥技术和盲签密思想,使用双线性对提出了一个新的基于无证书的盲签密方案。分析表明,新方案保持了盲签密的各种安全特性;解决了基于证书和基于身份密码体制中的证书存在的问题和密钥托管问题;在计算量方面,该方案只需两次双线性对运算,效率非常高。     

高效的无证书签密方案

无证书的密码体制不但消除了传统公钥密码体制中的证书管理问题,而且解决了基于身份密码体制中的密钥泄露问题。签密方案结合了公钥加密和数字签名的功能,能够同时实现消息的机密性和认证性。提出一种新的无证书签密方案,新方案在签密过程中需要1次配对运算,在解签密过程中仅需要3次配对运算。与已有的方案相比,新方案具备更高的效率。在安全性方面,新方案满足机密性、不可伪造性和可公开验证性。     

一类高效的无证书代理盲签名方案

已有的代理盲签名方案主要是基于传统公钥密码系统(PKI)以及基于身份的公钥密码系统(ID-PKC)提出的,它们分别存在看证书存储、管理以及密钥托管等问题.为避免上述问题,在无证书公钥密码系统上利用双线性对的知识提出了一种高效的无证书代理盲签名方案,该方案不仅具有较高的效率,满足代理盲签名要求的所有性质,而且克服了它们所...     

一个高效的基于证书数字签名方案

基于证书公钥密码学是Gentry在Eurocrypt 2003上首次提出的,它克服了传统公钥系统中存在的证书管理问题和基于身份公钥系统中存在的密钥托管问题。基于计算性Diffie-Hellman假设,构造一个Shnorr型的高效的基于证书数字签名方案,并在随机预言机模型（Random Oracle Model）下证明其安全性。该方案在签名算法中不需要任何双线性对运算,在签名验证算法中只需要一个双线性对运算,在效率上优于已有的基于证书数字签名方案。     

一个高效的基于证书签名方案

基于证书的公钥密码体制需要对用户的公钥进行认证,简化了传统的公钥密码系统中的证书管理过程,也克服了基于身份密码体制中存在的密钥托管问题。在随机预言机模型下,基于离散对数问题（DLP）,逆Diffie-Hellman问题（Inv-DHP）和计算性Diffie-Hellman问题（CDHP）构造了一个基于证书的签名方案,证明了它是存在性不可伪造的。该方案的算法只需要一个双线性对运算和一个预运算,在效率上优于已有的基于证书签名方案。     

不含双线性对的无证书签密方案安全性分析与改进

无证书密码体制能同时解决传统公钥密码体制证书管理问题和基于身份密码体制中密钥分发的问题,而受到学者们的关注。基于双线性对的无证书签密,因需要大量开销用于双线性对运算而性能不佳。研究不基于双线性对的无证书签密方案,发现Selvi等人的不基于双线性对的无证书签密方案不是标准的无证书签密方案,因为用户在使用时必须先验证对方的公钥,这不仅与无证书公钥体制相背,而且增加了用户的开销。分析了其他3个不基于双线性对的无证书签密方案,发现这3个方案都不满足不可伪造性和机密性。为解决这些安全性问题,提出一个新的不基于双线性对的无证书签密方案,并在随机预言机模型下证明了其安全性。     

一种可证明安全的有效无证书签密方案

无证书密码体制消除了基于身份密码系统中固有的密钥托管问题,同时又克服了传统公钥密码系统中复杂的证书管理问题,它具有两者的优点。签密是一个通过数字签名和公钥加密而同时实现认证和保密的密码学原语,而它却比分别签名和加密具有更低的计算量。提出了一种可证安全的无证书签密方案,其只在解签密阶段需要两个双线性对计算,因而具有较高的效率。最后,在随机预言模型下利用困难问题假设证明了方案满足适应性选择密文攻击下的不可区分性以及适应性选择消息和身份攻击下的存在不可伪造性。     

高效的基于证书数字签名设计方案*

基于证书加密结合了传统公钥密码加密和基于身份加密的优点,并克服了这两类加密体制中存在的问题。在计算性Diffie-Hellman问题困难的假设下,利用双线性对,构造了一个基于证书的数字签名方案,并在随机预言模型下证明了方案的安全性。方案设计简单,签名算法中不需要双线性对运算,仅在签名验证算法中存在一个双线性对运算,非常适合使用在计算能力和带宽受限的环境。     

高效可证安全的基于证书数字签名方案

基于证书公钥密码系统是近年来提出的一种新型公钥密码体制,它结合了传统公钥密码体制和基于身份密码体制的优点,克服了其存在的问题。利用双线性映射,提出了一个基于证书的数字签名方案,在随机预言机模型下给出了严格的安全证明。方案的安全性基于q强Diffie-Hellman问题和扩展的逆计算Diffie-Hellman问题的困难性。分析表明,所构造的新方案满足正确性和存在不可伪造性,具有较高的安全性,不仅简化了证书管理过程,克服了密钥托管问题,而且方案的整体性能比较高。     

基于IBC数字签名机制在电厂SIS中的应用

基于身份的密码系统使得用户的公钥能够通过用户的身份信息直接计算出来,不需要保存每个用户的公钥证书,避免了使用证书带来的存储和管理开销的问题,简化了基于证书的密码系统繁琐的密钥管理过程,并对基于身份的公钥系统和基于证书的公钥系统进行了比较和讨论.最后构建了基于双线性对和基于身份的数字签名解决方案,并对方案的安全性和效率作了分析.     

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QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。     

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。