可编程可伸缩的双域模乘加器研究与设计

模乘和模加减作为椭圆曲线公钥体制的核心运算,在ECC算法实现过程中使用频率极高。如何高效率、低成本地实现模乘模加减是当前的一个研究热点。针对FIOS类型Montgomery模乘算法和模加减算法展开研究,结合可重构设计技术,并对算法进行流水线切割,设计实现了一种能够同时支持GF(p)和GF(2n)两种有限域运算、长度可伸缩的模乘加器。最后对设计的模乘加器用Verilog HDL进行描述,采用综合工具在CMOS 0.18μm typical工艺库下综合。实验结果表明,该模乘加器的最大时钟频率为230 MHz,不仅在运算速度和电路面积上具有一定优势,而且可以灵活地实现运算长度伸缩。     

可伸缩双域Montgomery乘法器的优化设计与实现

模乘运算是公钥密码算法中的关键运算,本文基于全字运算的Montgomery模乘算法,设计了具有可伸缩硬件结构的模乘器。该模乘器可以基于固定的数据路径宽度对任意长度的数据进行运算,并且能够支持两个有限域上的运算。最后用Verilog硬件描述语言对该乘法器的硬件结构进行代码设计,并用Synopsys公司的Design Complier在Artisan SIMC 0.18μm typical工艺库下综合。实验结果表明,相对于其他模乘器设计,本文设计具有较高的时钟频率,并且由于大大减少了运算所需的时钟周期数,模乘运算速度较快。     

改进的蒙哥马利算法及其模乘法器实现

模乘运算的速度决定了公钥加密系统和众多通信系统的系统性能。通过分析Walter等学者对蒙哥马利算法的研究成果,得到运算精简基2-MMM算法,实现基于运算精简算法的线性脉动阵列模乘法器。在验证改进算法正确性后,对模乘法器进行功能仿真和综合。用TSMC 0.18 μm标准单元库综合,可以工作在200 MHz时钟下,等效单元为42 k门,完成1 024 bit模乘法运算需     

一种新型操作数长度可伸缩的模乘器VLSI设计

在改进基于字的Montgomery模乘算法的基础上，通过优化流水线结构缩短关键路径，实现了一种结构优化的模乘器。设计中采用了按字运算的高基Montgomery模乘算法，使该设计具有良好的可扩展性，可以完成任意位数的模乘运算。改进了模乘器的流水线结构，提高了模乘器的工作效率。该设计可以应用于各种高性能且低成本的RSA密码协处理器设计。     

基于高基阵列乘法器的高速模乘单元设计与实现

蒙哥马利模乘算法是最适合硬件实现的模乘算法,被应用在RSA密码和ECC密码的协处理器设计中.目前性能最高的是高基蒙哥马利模乘算法,分析了高基蒙哥马利算法的实现,提出了一种新的基于高基阵列乘法器的Montgomery模乘高速硬件实现结构,基于这种结构位长为n的比特模乘仅需要约n/w+6个时钟周期,该结构设计的电路只与最小单元有关,在硬件实现时可以大大提高频率,并提高设计的性能,可以设计高速的RSA和椭圆曲线密码大规模集成电路.     

一种高性能大数模运算单元及其应用

为了加速公钥密码系统的实现速度,设计支持大教模乘和模加减运算的模运算单元是关键.目前的方法多关注于这两种运算的分别实现,为了改善这种方式导致的硬件单元吞吐量低的问题,提出了一种流水线结构的高性能大数模运算单元.基于改进的Montgomery模乘算法,采用流水线技术,把模乘电路分成3个流水线阶段,并把模加减电路结合到第3阶段,得到一种能同时计算模乘和模加减的模运算单元.仿真结果显示,模运算单元以较少的资源占用率获得了较高的吞吐量,非常适合做高性能的公钥密码系统的基本硬件运算单元.     

基于FPGA的Montgomery模乘器的高效实现*

为了提高椭圆曲线密码处理器的模乘速度,本文提出了一种更有效且更适合硬件实现的Montgomery算法。改进的算法分析了基于CSA加法器的Montgomery模乘算法,提出了多步CSA加法器的Montgomery算法,该算法能够在一个时钟内做多次CSA迭代运算,可以有效地降低时钟个数,进而提高模乘速度。通过Modelsim仿真工具仿真,正确完成一次256bits Montgomery模乘运算只需要16个时钟周期。在Altera EP3SL200F1517C2 FPGA中的运行结果表明：71.5MHz的时钟频率下,完成一次256位的模乘运算仅需要0.22微秒。     

一种可重构模乘器的硬件设计

提出一种改进的基于剩余数系的Montgomery模乘算法.该算法通过对相对固定的参数进行预计算,从而减少运算过程中模乘运算的次数,与Bajard J C提出的算法(IEEE计算机会刊,2004第6期)相比减少300/(2k+8).同时基于改进算法提出数据长度可伸缩的硬件模乘器结构设计,并在0.18 μm SMIC工艺下...     

SM2算法模逆加速器的设计

SM2公钥密码在智能卡领域有广泛的应用,其运算中难以避免模逆运算,而模逆算法因为其具有幂指数级别的运算复杂度,成为制约SM2算法性能的一个重要瓶颈。以SM2算法公钥引擎为基础,巧妙地利用了已有的蒙哥马利乘法器结构,设计出了一种长度可伸缩的快速模逆算法。并复用已有模乘资源,给出了节省存储空间、不增加面积成本的硬件实现结构以及数据存储方案。其速度性能远远优于传统的费马小定理算法和扩展欧几里德算法,对比同类蒙哥马利模逆算法也有良好的性能。     

RSA高速模乘单元的设计

论文分析了Montgomery算法,利用迭代加法之间的并行性提出了一种流水并行工作的硬件模乘结构。该结构具有时钟频率高,模幂运算时间短的优点,适合于RSA的模幂运算,可以极大提高RSA加密运算的效率,同时其体系结构适合于高阶Montgomery算法的实现。FPGA实现的结果表明,512位的高速模乘单元工作频率74.27MHZ;1024位的高速模乘单元工作频率73.94MHZ。模乘单元的面积与位宽成正比,而工作频率基本不变。基于此结构,512位的RSA运算时间为1.78ms,1024位的RSA运算时间为7.08ms。     

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.