基于TePA的无线传感器网络安全方案

针对无线传感器网络的安全需求, 结合TePA技术提出了一种基于TePA的无线传感器网络安全方案。该方案简化了TePA技术的身份认证分组和分组字段, 解决了无线传感器网络在传感器节点接入和密钥协商的问题。采用改进的BSW逻辑验证了协议, 并从协议安全性和网络性能方面分析了方案, 结果表明方案能抵抗中间人攻击和重放攻击, 并适合无线传感器网络。     

基于Merkle难题的P2P网络匿名认证方案

现有的认证方案大多采用超级节点或者引入CA认证中心进行节点间认证,破坏了P2P网络分布式特点;此外,认证过程一般使用节点的真实ID,不能满足P2P网络匿名性的需求。针对以上问题,文中提出一种结合Merkle难题和改进的SAKA算法的节点间匿名认证方案MBAA（Merkle—based Anonymous Authentication）。该方案使用Merkle难题产生和安全传输SAKA算法所必需的对等节点间的初始共享密钥,并采用基于单向散列函数认证的SAKA算法,实现了P2P网络中节点之间的分布式匿名认证。理论分析表明,MBAA可以有效抵御中间人攻击、重放攻击和密码猜测攻击,是一种安全有效的匿名认证方案。     

一种轻量级的Ad Hoc网络会话密钥建立方案

Ad Hoc网络是一种不依赖于任何固定基础设施、没有中心控制节点,计算资源受限的新型无线移动网络.本文基于SCHNORR签名方案,提出了一个新的适用于Ad Hoc网络的基于口令认证和口令进化的轻量级双方密钥协商方案.新方案具有抗中间人攻击、抗重放攻击、密钥独立和前向安全等多种安全特性.     

无线传感器网络安全认证方案综述

安全认证是无线传感器网络中关键安全技术之一,如何确保无线传感器网络中通信双方身份的真实性是无线传感器网络的一个研究重点.论文从基于对称密码体制、非对称密码体制的认证方案、分布式认证方案、单向散列函数的认证方案、零知识证明的认证方案等方面出发,对典型的无线传感器网络认证方案进行了总结归纳,并指出了每类方案优点与不足,最后对无线传感器网络中安全认证方案的研究热点进行了展望.     

无线传感器网络中基于节点行为和身份的可信认证

针对无线传感器网络(WSN)开放性和资源受限导致易受外部和内部攻击以及节点失效等问题,提出了一种高效、安全的可信节点间身份认证方案。方案采用基于身份和双线性对理论实现认证密钥协商与更新,通过基于Beta分布的节点行为信誉的管理计算其信任度,利用信任度识别节点是否可信并采用对称密码体制结合信息认证码实现可信节点间认证。方案不仅能防范窃听、注入、重放、拒绝服务等多种外部攻击,而且能够抵御选择性转发、Wormhole攻击、Sinkhole攻击和女巫攻击等内部威胁。与SPINS方案相比,所提方案在同一网络环境下有较长的网络生命期、较小的认证时延、更高的安全性及可扩展性,在无人值守安全性要求较高的WSN领域具有较好的应用价值。     

一个无线Hand-Off认证协议的分析与改进

通过分析文献[1]中Wang提出的一个匿名移动无线认证方案中的Hand-Off认证协议,发现了其存在安全漏洞,无法抵抗中间人发起的重放攻击,针对该协议存在的安全漏洞对原协议进行了改进,改进后的协议可以安全的实现用户与机站之间的身份认证,并可以有效地抵抗中间人发起的重放攻击。     

基于分簇的无线传感器网络密钥预分配方案

在无线网络传感器防止虚假攻击保证网络安全问题的研究中,针对无线传感器网络中的安全和提高系统识别认证能力问题,为了实现无线传感器网络中的安全通讯,需要对传感器节点间传递的信息进行加密.传统网络中使用的密钥分配策略,并不适用于无线传感器网络.分析了已有无线传感器网络密钥分配方案的特点.为了提高网络通信的安全性,尤其是在部分传感器节点被捕获后整个网络的健壮性,在分配方案基础上,采用一种分簇网络体系的密钥预分配方案.实验结果保证了连通率,节约存储空间,证明适用于现有的无线传感器网络.     

基于Merkle树的无线传感反应网络的公钥认证机制

公钥加密(PKC)已被证明能在资源受限的传感器节点中部署.为了防止中间人攻击,网络节点的公钥在节点通信前需要相互认证.为此,提出了一种基于Merkle树和位置部署知识的密钥认证机制.与公钥加密RSA算法和椭圆曲线加密算法相比,该机制通过使用单向Hash函数和利用无线传感反应网络节点异构等特性有效地降低了公钥认证的计算复杂性和能量消耗,并使得认证机制在无线传感反应网络的通信开销和异构节点内存消耗得到最佳平衡.     

无线传感网动态可认证群组密钥交换协议

无线传感器网络中节点电池电量有限、节点计算能力及存储能力受限,使得现有的大部分群组密钥交换技术不适用于无线传感器网络。针对该问题,提出一种动态的可认证群组密钥交换协议。采用双线性映射技术实现无线传感器网络中节点之间的群组密钥交换。该协议具有可认证性,避免群组密钥交换过程中遭到欺骗攻击及中间人攻击;具有动态性,适用于无线传感器网络节点动态部署;在双线性计算Diffie-Hellman(bilinear computation Diffie-Hellman,BCDH)困难性假设下是可证安全的。分析结果表明,该协议具有较高的安全性和较好的性能。     

移动场景下异构无线传感器网络密钥管理方法

由于移动无线传感器网络支持节点的移动性,使其面临更加复杂的安全性挑战,很难防御一些极具破坏力的攻击,比如节点复制攻击和女巫攻击等。本文提出了在移动异构无线传感器网络模型下一种安全高效的密钥管理方法。所提方法采用椭圆曲线密码学加密算法实现移动节点位置信息到基站的安全上传,以及基于密钥哈希的消息认证码来实现消息源的身份认证。基站则对收集的移动节点位置信息进行统计分析来协助完成固定节点与移动节点间的身份认证及会话密钥建立。实验结果表明,所提方法在密钥建立过程节省了网络资源,同时可有效防御攻击者发起重放攻击、节点复制攻击和女巫攻击等,增强了网络安全性。     

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。     

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.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).