认证协议中数据同步的分析

认证双方数据的同步是认证协议以及认证密钥交换协议的基本要求,但是在协议设计过程中难以把握且经常被忽视。对近年来可证明安全的一个RFID认证协议和一个RFID认证密钥交换协议以及可证明安全的一个移动卫星通信系统认证密钥交换协议进行了仔细分析,分别发现了针对这些协议的数据同步攻击,这些攻击破坏了协议的可用性。最后分别给出了改进方案,以克服存在的安全隐患。     

一种WLAN的新安全标准CCMP协议

新一代WLAN安全标准IEEE 802.11 i定义了三种协议来保护数据的传输,这三种协议增强了WLAN中数据的加密和鉴别性能,取代了IEEE 802.11 WEP方案。CCMP协议是数据保密协议之一。CCMP协议使用基于AES的加密算法和CCM加密鉴别模式,在软件和硬件实现上都提供了很好的安全性能。     

IPSec网络安全构架

IPSec是网络层的安全协议标准,它提供了IP层上的多种安全服务。本文对IPSec的工作原理、工作模式,及其主要的两个安全协议进行了分析。     

分布式密钥分发方案的安全性证明

复合协议的安全性是当前国际上的热点问题，应用复合协议的观点证明了Daza等人提出的分布式密钥分发方案是安全的，该方案在抵抗被动敌手攻击方案的基础上添加了可验证秘密分享和零知识证明，以抵抗主动敌手的攻击，从而具有更高的安全性。     

双主体认证协议抵御DoS攻击的安全方案

认证协议存在的一定的拒绝服务(DoS)攻击隐患。该文在cookie机制和工作量证明方法思想的基础上,采用弱认证和强认证相结合的方法,提出了双主体认证协议抵御DoS攻击的安全方案,给出了方案的实现细节和部分实验数据,分析了该方案的安全性。应用该方案对Lowe的NSPK协议进行改进,并分析了改进后协议的性能。     

双连接文件安全传输的设计与实现

针对文件传输存在的安全性缺陷,提出了一种基于转发模式的双连接文件安全传输方法。采用转发隔离思想设计了双连接结构,对文件存储服务器和客户端进行隔离,通过文件安全传输协议栈实现数据的全程加密和可靠传输,并讨论和解决了双连接结构的数据传输引起的流量控制问题。实验结果表明,基于转发模式的双连接文件安全传输在确保服务器安全性和数据密文传输的同时,保障了文件传输的速度和效率。     

基于802.11i的无线局域网安全加密技术研究

为了提高无线局域网的安全性,解决传统安全机制WEP协议中所存在的缺陷,给出了一种基于IEEE802.11i的无线局域网安全模型.在分析了IEEE802.11i协议的体系结构和安全机制的基础上,对IEEE802.11i的数据加密技术进行了剖析,详细分析了TKIP和CCMP协议的加解密过程和安全性能,结果表明,TKIP的安全性能仍有局限性,只是一种过渡方案,而CCMP才是健壮的数据保密协议.     

应用于无线局域网的IPSec VPN安全解决方案

文章着重讨论虚拟专用网vPN及IP安全协议IPSec等在无线局域网安全领域的应用。在分析VPN和IPSec的基础上，强调了IPSec VPN作为WLAN建网实践中的安全技术，业已成为目前各种解决WLAN安全问题技术方案的首选方案。     

Windows下RDP协议的安全性

微软开发的Windows下的RDP协议暴露出一定的安全问题。介绍了RDP协议的工作原理，分析了RDP采用的安全机制，指出其在协议设计上存在的一些漏洞，从用户使用和协议改进两个方面分别提出了防范措施和修改方案。     

基于IE安全交易协议的网上支付系统方案研究

网上支付系统是网上报考管理信息系统的核心内容之一。本文从分析Internet主要的安全交易协议入手，对SET协议和SSL协议进行了比较，提出了在线支付系统实现的两种方案，从系统的实际情况出发。综合考虑这两种方案的利弊和可操作性，提出方案选择。     

关于一种网格运行时结构的若干注记

进程是传统计算机系统的一个核心概念，自1960年出现以来一直沿用至今，进程的一个主要目的是为主体提供一种运行时结构，在操作系统和处理器硬件支持下，代表主体访问和使用各种资源，与传统的单机和并行机计算平台相比，网格计算机中进程所对应的概念面临新的挑战，包括网格资源繁杂、自主控制的条件下的单一系统映像和资源的共享与协同、与特定操作系统的松耦合、时间和空间的流动性、更高级的交互性，提出一种称为网程(grip)的运行时结构，试图解决上述问题，网程运行在网格操作系统之上，代表网格主体，访问和使用网格资源。     

Virtual Triangulation Sensor Development, Behavior Simulation and CAR Integration Applied to Robotic Arc-Welding

Background: An increasing number of industrial robots are being programmed using CAR (Computer Aided Robotics). Sensor guidance offers a means of coping with frequent product changes in manufacturing systems. However, sensors increase the uncertainty and to preserve system robustness, a tool is needed that makes it possible to understand a sensor guided robot system before and during its actual operation in real life.Scope: A virtual sensor is developed and integrated in a CAR hosted environment. The real sensor is of a type commonly used in the arc-welding industry and uses a triangulation method for depth measurements. The sensor is validated both statically and dynamically by matching it with a real sensor through measurements in setups and by comparing a welding application performed in a real and a virtual work-cell created with a CAR application. The experimental results successfully validates its performance. In this context, a virtual sensor is a software model of a physical sensor with similar characteristics, using geometrical and/or process specific data from a computerized model of a real work-cell.     

Design of phononic materials/structures for surface wave devices using topology optimization

We develop a topology optimization approach to design two- and three-dimensional phononic (elastic) materials, focusing primarily on surface wave filters and waveguides. These utilize propagation modes that transmit elastic waves where the energy is contained near a free surface of a material. The design of surface wave devices is particularly attractive given recent advances in nano- and micromanufacturing processes, such as thin-film deposition, etching, and lithography, which make it possible to precisely place thin film materials on a substrate with submicron feature resolution. We apply our topology optimization approach to a series of three problems where the layout of two materials (silicon and aluminum) is sought to achieve a prescribed objective: (1) a grating to filter bulk waves of a prescribed frequency in two and three dimensions, (2) a surface wave device that uses a patterned thin film to filter waves of a single or range of frequencies, and (3) a fully three-dimensional structure to guide a wave generated by a harmonic input on a free surface to a specified output port on the surface. From the first to the third example, the resulting topologies increase in sophistication. The results demonstrate the power and promise of our computational framework to design sophisticated surface wave devices.     

基于RFID的磁盘加密系统

文章在跟踪和分析最新磁盘加密技术研究成果的基础上,设计了一种基于RFID的磁盘分区加密系统。该系统由磁盘分区加密软件Partition Crypt与RFID射频卡、USB射频读写端等硬件模块共同组成。软件部分对计算机硬件系统要求低、安装方便、使用简单、加密效果好;硬件部分由单片机与射频模块完成。其中,USB接口采用虚拟USB接口的方法,降低硬件复杂性与成本,具有很高的性价比。经过测试,整个系统功能稳定、性价比高、保密性好,可为广泛使用的基于Windows操作系统的涉密计算机提供加密技术保障,应用前景广阔。     

Catadioptric Projective Geometry

Catadioptric sensors are devices which utilize mirrors and lenses to form a projection onto the image plane of a camera. Central catadioptric sensors are the class of these devices having a single effective viewpoint. In this paper, we propose a unifying model for the projective geometry induced by these devices and we study its properties as well as its practical implications. We show that a central catadioptric projection is equivalent to a two-step mapping via the sphere. The second step is equivalent to a stereographic projection in the case of parabolic mirrors. Conventional lens-based perspective cameras are also central catadioptric devices with a virtual planar mirror and are, thus, covered by the unifying model. We prove that for each catadioptric projection there exists a dual catadioptric projection based on the duality between points and line images (conics). It turns out that planar and parabolic mirrors build a dual catadioptric projection pair. As a practical example we describe a procedure to estimate focal length and image center from a single view of lines in arbitrary position for a parabolic catadioptric system.     

An Interactive Designing System with Virtual Sculpting and Virtual Woodcut Printing

In this paper, we propose an interactive designing method and a system based on it to create 3D objects and 2D images. This system consists of two subsystems for virtual sculpting to create a 3D shape and virtual printing to produce a picture with a printing block. In the virtual sculpting subsystem, a user can form solid objects with curved surfaces as if sculpting them. The user operates virtual chisels, and can remove or attach arbitrary shapes of ellipsoids or cubes from or to the workpiece. A 3D object generated by virtual sculpting looks like a real wooden sculpture. If using a board as a workpiece, a user can generate a virtual printing block. In the virtual printing subsystem, a user can synthesize a woodcut printing image from the virtual printing block mentioned above, a virtual paper sheet, and a printing brush. The user can synthesize a realistic woodcut print with a procedure similar to the actual woodcut printing.     

ROD-based hybrid TH precoding and combining for mmWave large-scale MIMO systems

Hybrid precoding is one of key techniques for millimeter wave (mmWave) large-scale multiple-input multiple-output (MIMO) systems. This paper considers a nonlinear hybrid precoding architecture which consists of a nonlinear unit, a reductive digital precoder and a constant modulus radio frequency (RF) precoder, and presents a novel hybrid Tomlinson-Harashima (TH) precoding and combining algorithm. Firstly, due to the intractability of the sum rates maximization problem for such a nonlinear hybrid precoding architecture, a tractable three-stage optimization problem is constructed through the lower bound of the sum rates, which allows the digital precoding matrix, the RF precoding matrix and the RF combining matrix to be optimized sequentially and independently. Then, in order to solve the three-stage optimization problem effectively, a novel row orthogonal decomposition (ROD) is defined. Based on the ROD, it is interesting that the necessary and sufficient condition of the optimal digital precoding matrix can be obtained, and a near-optimal RF precoding matrix can be derived. Finally, the optimization of the RF combining matrix is reformulated as a unimodular quadratic programming and solved by a generalized power method. Theoretical analyses and simulations indicate that the proposed ROD-based hybrid TH precoding and combining algorithm can offer a higher sum rates and a lower bit error rate with a comparable complexity in comparison to the previous works.     

On the equivalence between small-step and big-step abstract machines: a simple application of lightweight fusion

We show how Ohori and Sasano's recent lightweight fusion by fixed-point promotion provides a simple way to prove the equivalence of the two standard styles of specification of abstract machines: (1) in small-step form, as a state-transition function together with a ‘driver loop’, i.e., a function implementing the iteration of this transition function; and (2) in big-step form, as a tail-recursive function that directly maps a given configuration to a final state, if any. The equivalence hinges on our observation that for abstract machines, fusing a small-step specification yields a big-step specification. We illustrate this observation here with a recognizer for Dyck words, the CEK machine, and Krivine's machine with call/cc.The need for such a simple proof is motivated by our current work on small-step abstract machines as obtained by refocusing a function implementing a reduction semantics (a syntactic correspondence), and big-step abstract machines as obtained by CPS-transforming and then defunctionalizing a function implementing a big-step semantics (a functional correspondence).     

CoolBar工具条的编写

介绍了如何使用Ｖｉｓｕａｌ Ｃ＋＋ ６．０来编写类似于Ｍｉｃｒｏｓｏｆｔ Ｉｎｔｅｒｎｅｔ Ｅｘｐｌｏｒｅｒ中具有扁平按钮、把手、文本标签、下拉列表和热点图象等新特点的工具条。     

Monocular Vision for Mobile Robot Localization and Autonomous Navigation

This paper presents a new real-time localization system for a mobile robot. We show that autonomous navigation is possible in outdoor situation with the use of a single camera and natural landmarks. To do that, we use a three step approach. In a learning step, the robot is manually guided on a path and a video sequence is recorded with a front looking camera. Then a structure from motion algorithm is used to build a 3D map from this learning sequence. Finally in the navigation step, the robot uses this map to compute its localization in real-time and it follows the learning path or a slightly different path if desired. The vision algorithms used for map building and localization are first detailed. Then a large part of the paper is dedicated to the experimental evaluation of the accuracy and robustness of our algorithms based on experimental data collected during two years in various environments.