串空间模型及其认证测试方法的一种扩展与应用

认证测试方法是基于串空间模型的验证安全协议的一种形式化方法,由于串空间模型没有抽象更多的密码学原语,因此难以分析较复杂的安全协议。通过扩展消息项、子项关系以及入侵者模型,扩展了串空间模型及相应的认证测试方法。根据扩展后的认证测试方法,分析了SSL3.0握手协议,验证了该协议认证属性。     

基于串空间的可信计算协议分析

可信计算技术能为终端、网络以及云计算平台等环境提供安全支撑,其本身的安全机制或者协议应该得到严格的形式化证明.该文基于串空间模型对其远程证明协议进行了分析.首先,扩展了串空间的消息代数和攻击者串,使其能表达可信计算相关的密码学操作,并对衍生的定理进行了证明;并且提出了4个新的认证测试准则,能对协议中的加密、签名、身份生成和哈希等组件进行推理.其次,基于扩展的串空间模型对远程证明协议的安全属性(隐私性、机密性和认证性)进行了抽象和分析.最后,给出了对发现攻击的消息流程,并基于ARM开发板对其中的布谷鸟攻击进行了实现,验证了串空间的分析结果.     

串空间和认证测试在协议分析中的应用

串空间模型是一种新兴的密码协议形式化分析工具.分别采用串空间模型争认证测试这两种前沿的形式化分析方法对X.509协议的认证性进行了分析,指出了该协议在认证正确性方面存在的缺陷.然后针对分析结论提出了改进协议,并使用认证测试方法证明了改进的协议能够实现认证的正确性.通过比较发现应用认证测试方法分析安全协议,比单纯应用串空间模型更为简洁和直观.     

协议主体密钥在测试组件构造上的性质分析

针对认证测试理论在测试组件构造方面缺少具体形式化构造规则的不足,根据协议主体在认证测试中的角色特点,以及包含惟一源发消息的消息组件在认证测试中的作用和性质,对消息组件进行分类和定义并提出认证测试模型的概念,基于认证测试模型给出协议主体密钥在测试组件构造上的性质命题,同时运用认证测试基础理论对命题进行正确性证明,从而确定测试组件构造的形式化规则。     

不同密码体制下挑战-应答协议的分析

挑战-应答协议只有满足特定的安全条件才能保证实现其认证目标,用串空间模型对满足约束条件的协议形式进行建模,分别在对称和非对称密码两种密码体制下用认证测试方法对双方的互认证性进行形式化地分析,找出协议的漏洞及其形成的原因.凭借测试元素进一步完善不同密码体制下挑战-应答协议的约束条件,以保证其实现互认证的要求,并为设计更复杂的认证协议提供依据.同时也从另一角度证明了基于串空间模型的认证测试方法在协议的形式化分析领域的重要价值.     

认证测试方法对TLS协议的分析及其应用

TLS(传输层安全)协议被广泛用来保证Web的安全,为了分析其安全性,用串空间模型对其进行形式化描述,并用认证测试方法分别对客户端和服务器端的认证性进行分析,证明协议存在中间人攻击,通过修改认证测试方法的测试元素对协议形式进行改进,并证明改进后协议的正确性.     

基于串空间模型安全协议形式化分析方法的研究

从串空间模型理论人手,提出了三种典型的串空间形式化方法(基于极小元理论的串空间方法、基于理想与诚实理论的串空间方法、基于认证测试理论的串空间方法),并对每一种方法的证明步骤及优缺点进行了分析.在此基础上,应用提出的串空间方法对Yahalom协议的秘密性和认证性进行了分析.分析结果表明利用不同方法的优点,能更好地保证安全协议形式化分析的准确性.     

突破认证测试方法的局限性

认证测试是一种用于证明安全协议认证属性的新方法,该方法能够简化协议认证属性的证明过程,但其局限性是无法应用于认证测试元素被多重加密的情况.指出Perrig和Song提出的认证测试改进方案在多个方面所存在的问题.在此基础上提出新的改进方案,并进行了形式化证明.新的认证测试定理突破了认证测试元素在整个协议消息中不能被加密的限制,扩展了认证测试理论的应用范围.     

Needham-Schroeder 协议的认证测试方法形式化分析

在安全协议的形式化分析方法中,串空间模型和基于串空间模型的认证测试方法是比较常用的验证方法。针对Needham- Schroeder协议存在中间人攻击的缺陷,提出对协议的改进并采用认证测试方法,验证了改进的协议可以满足协议的安全目标。     

认证测试中协议主体串参数一致性研究

针对认证测试基础理论在协议主体串参数一致性分析方面,因形式化判定规则不足所产生的分析复杂度较高和自动化程度较低问题,通过对消息组件结构的形式化,以及认证测试结构的共性分析,基于认证测试基础理论对认证测试结构进行形式化建模;在认证测试结构模型上,运用协议主体密钥的认证测试构造规则,分析协议主体串在不同类型参数上满足一致性的条件,在明确参数一致性判定规则的同时,给出协议主体串参数一致性分析的形式化方法。协议分析实践表明,该方法较传统方法不仅具有简洁高效、易于自动化实现的优点,而且能够准确定位协议缺陷并给出相应的修正方案。     

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.