一种新的基于双线性配对的无线传感网络密钥协商方案

针对无线传感器网络密钥协商中安全性不足的问题,提出了一种适合无线传感器网络的密钥协商方案KASBP。该方案首先运用基于双线性配对的运算预置网络系统参数并通过计算获得节点的相关参数;然后节点向邻居节点广播,并利用Diffie-Hellman密钥交换技术,使节点间能够共享密钥。理论分析结果表明,KASBP方案的执行效率不仅优先于LZC和Shim-Woo的密钥协议方案,同时也符合已知密钥安全完美前向安全密钥泄露安全未知共享密钥安全密钥支配安全等安全需求。     

无线传感器网络中三方密钥建立协议研究

提出了一个无线传感器网络(WSN)的可证明安全认证三方密钥建立协议。协议的安全性基于求解椭圆曲线离散对数问题和双线性配对Diffie Hellman问题的计算不可行性。节点之间的身份验证是无线传感器网络中最具挑战性的一个安全要求,它需要在WSN中三个相邻节点之间建立正确的会话密钥轮来实现这种安全目标。通过理论证明,该协议对数据完整性攻击和会话密钥中已知密钥安全性攻击是安全的,并提供了完美的前向安全。     

基于双线性对的WSN密钥协商和认证协议

无线传感器网络(WSN)节点在电源、计算能力和内存容量等方面存在局限性,且面临的安全威胁更复杂。为此,提出一种适用于类LEACH路由的WSN密钥协商和认证协议。通过引入当前轮数,实现节点间的双向身份认证,以抵御选择性转发、Sybil和Hello泛洪等常见攻击。利用ID和双线性对原理生成节点间的动态会话密钥,从而减少节点间的交互步骤,降低能耗。SVO逻辑推理和性能分析结果表明,该协议同时满足安全性要求和WSN的特殊应用要求。     

基于双线性对的WSN节点认证协议

针对无线传感器网络节点在能量、通信和存储等资源受限的情况,以及网络所面临的各种安全威胁,基于椭圆曲线双线性对提出了一种基于身份的节点认证协议。节点私钥由自己生成,基站签名节点公钥,保证了协议的私钥泄露和密钥托管安全。仅一次的交互次数为传感器节点大大节省了通信能量。安全的认证协议可有效抵制无线传感器网络所面临的节点复制攻击、Wormhole攻击、Sinkhole攻击和女巫攻击。     

基于身份的可认证非对称群组密钥协商协议

非对称群组密钥协商协议(asymmetric group key agreement,AGKA)能使群组内部成员安全地传递信息.随着大规模分布式网络协同计算的发展,参加安全协同计算的成员可能来自于不同领域、不同时区、不同云端及不同类型的网络.现有的AGKA不能满足来自于跨域及异构网络之间群组成员的安全信息交换,且安全性仅局限于抗被动攻击.提出一种基于身份的可认证非对称群组密钥协商协议(identity-based authenticated asymmetric group key agreement,IB-AAGKA),该协议实现一轮非对称群组密钥协商,解决群组成员因时区差异而不能保持多轮在线密钥协商的问题;可实现匿名性与可认证性;支持节点的动态群组密钥更新,实现了群组密钥向前保密与向后保密安全性.在decisional bilinear Diffie-Hellman(DBDH)困难假设下,证明了协议的安全性,并分析了协议的性能.     

无线传感器网络节点间认证及密钥协商协议

无线传感器网络的特性使它面临着比传统无线网络更大的安全挑战,其安全解决方案必须兼顾安全性和系统性能等因素。节点间认证及密钥协商是构建安全网络最基本的协议,是密钥管理协议和安全路由协议等的实现基础。很明显,包括传统Adhoc在内的各种无线网络领域中的安全认证及密钥协商机制都无法适用于无线传感器网络。为此,在充分考虑无线网络攻击方法和无线传感器网络自身特点的基础上,结合基于ID的公钥密码技术,提出了椭圆曲线双线性对上的无线传感器网络节点安全认证及密钥协商协议。分析发现,该协议不仅满足安全性要求,同时,能够适合无线传感器网络的特殊应用要求。     

非平衡网络环境下基于身份的组密钥交换协议

针对参与者计算能力不均衡的非平衡无线网络环境,首先对基于身份的群组认证密钥协商(ID-AGKA)协议进行安全性分析,指出该协议不能抵抗临时密钥泄露攻击; 随后通过对该协议签名的生成方式进行改进,使得改进的协议不仅在安全性上有所提高,而且能有效减少计算代价和通信代价,因此更适用于非平衡无线网络; 同时,协议采用了指定验证者签名,能有效地解决签名者的隐私问题; 此外,对非平衡网络中群组密钥协商协议的动态机制进行改进,通过高能量节点合理利用用户动态变化前计算的信息来减少低能量节点不必要的计算,这一改进能极大减少低能量节点的计算代价,更符合实际需求; 最后,在随机预言模型中基于整除判定性Diffie-Hellman(DDDH)假设证明了改进的群组密钥协商(GKA)协议的安全性.     

基于CK模型的安全节点认证密钥交换协议

无线传感器网络中的节点常常被部署在非安全的环境中,因而容易遭受假冒等安全威胁。为保护可信节点之间数据通信安全,基于计算性Diffie-Hellman假设,提出一种节点认证与密钥交换协议。推荐方案不仅能实现对参与节点真实身份的鉴别,而且生成一个参与方共享的秘密密钥,为参与方之间的数据交换建立一个安全的通信信道。并证明了推荐方案能实现CK模型下认证和密钥协商的协议的安全目标。此外,对安全属性的分析表明该协议具备前向安全、已知会话密钥安全、抗密钥泄漏假冒及未知密钥共享攻击的能力。     

基于双线性对的WSN密钥管理和认证方案*

针对无线传感器网络节点在电源、计算能力和内存容量等方面的局限性,以及当前所面临比传统网络更复杂的安全威胁,提出了一种基于双线性对的无线传感器网络密钥管理和认证方案。通过由第三方PKG签名一个包括节点身份和时间标记的数据包,解决了新加入网络节点的身份审核问题,能够抵御传感器网络中大多数常见的攻击。利用双线性对生成节点间的会话密钥,减少节点之间的交互步骤,降低了能量的开销,并加入了一个随机数,解决了密钥托管问题。最后对方案的安全性和可行性进行了分析。     

WSN中基于非双线性对的无证书群组密钥协商协议

针对无线传感网(Wireless Sensor Network,WSN)群组密钥协商协议计算开销较大的问题,提出一种基于非双线性对的无证书群组密钥协商协议。在系统初始化阶段,协议通过无证书加密体制的密钥生成中心生成节点部分私钥,各个节点依据秘密值与对应的部分密钥相乘产生私钥;在节点认证阶段,协议基于椭圆曲线上的点乘运算提出节点认证机制,利用节点的部分私钥与具有身份信息的临时公钥进行点乘运算来确定节点的身份信息;在生成会话密钥阶段,通过点乘运算生成会话密钥,以降低节点的计算开销。最后,分析了协议的计算开销和通信开销。结果表明,所提出的群组密钥协商协议能保证群组节点通信的安全性,并有效降低群组节点通信的计算开销。     

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).