RSA密钥强度量化与筛选模型的分析与研究

RSA算法在信息安全领域应用很广,其安全性经受了数十年的考验.然而,密钥安全不同于算法安全,它常为人们所忽视.在大多数实现中,人们对RSA密钥本身的安全性缺乏认识,这样,即使采用强算法也会引发安全问题.围绕RSA密钥的安全性度量问题,从已知明文的RSA攻击出发,提出了对RSA密钥安全性进行度量的数学模型和密钥安全系数的概念系统,分析了安全强度系数.密钥数量的分布,设计了对密钥强度量化的方法,改进了RSA密钥产生算法.并对其在深腾1800集群平台上进行了仿真分析,对于增强RSA算法实现的安全性有着积极的参考意义.     

PGP邮件系统核心算法分析及安全性的改进

从PGP原理入手,对PGP邮件系统的核心算法MD5信息-摘要算法、RSA数字签名算法、IDEA加密算法的原理和安全性进行了详细的研究.提出了用RIPEMD-160摘要算法代替MD5摘要算法、用基于椭圆曲线的签名算法代替RSA签名算法的技术改进.并对改进算法后的PGP邮件系统性能进行理论分析和测试,得出它们具有很高的安全性和可靠性.这样使基于PGP技术的电子邮件系统更具安全性.     

改进RSA算法的分析研究

RSA算法因其安全性、易用性受到广泛的应用,但其密钥的长度和运行速度之间存在着一定的矛盾,成为算法进一步发展的障碍。本文通过对传统RSA算法进行分析研究,针对其速度缺陷提出改进的N重RSA算法,实验结果表明改进后的算法实现效率提高,具有一定的应用推广价值。     

基于多素数和参数替换的改进RSA算法研究

为了提高RSA公钥算法在消息加密过程中的安全性,在深入分析传统RSA算法的基础上,对其进行一些改进性研究,提出了一种比传统RSA算法更加有效的方法优化其安全性。在将传统RSA改进为四素数RSA的基础上,再运用数学变换进行参数替换,消除了在公钥中对传输两个随机素数的乘积n的需要,引入了一个新的参数x代替原参数n。针对改进后的算法在运算效率方面的不足,采用中国剩余定理( Chinese remainder theorem,CRT)优化大数模幂运算。实验结果证实了改进算法的可行性,为通过公钥加密消息发送和接收提供了更安全的路径;同时,对改进算法与传统RSA 和四素数RSA算法的解密(签名)时间进行比较分析。实验结果表明改进后的算法对消息发送方和接收方之间签名效率也有一定程度的优化。     

DES_RSA及其混合算法的加密速度研究

为了在保证安全性的前提下提高大量数据加密的加密速度,本文通过DES和RSA算法的分析,针对DES算法密钥安全性差和RSA算法加密速度慢的问题,提出DES和RSA混合算法.对比DES和RSA两种算法加密所需时间,就RSA算法耗时长的问题,通过几种可行的大素数判定算法分析,提出改进的大素数判定算法.在保证安全性的前提下,将改进的大素数判定算法应用于RSA算法中,提升了加密速度.由于改进算法加密速度仍远差于DES算法,不适合大量数据加密.因此在兼顾安全性与加密速度的基础上,提出DES和RSA混合加密算法.经分析该算法综合了前两种算法的优点,是一种理想的加密算法.     

对一种多重数字签名方案的攻击和改进

对Zhang等人提出的基于身份的RSA多重数字签名方案进行安全分析,提出了一个完全攻击算法。首先介绍了Zhang签名方案以及攻击算法,然后针对此签名算法的安全缺陷,提出了两个改进方案。改进方案均修改了每个签名者的随机化处理过程,并转移了部分计算操作。结果表明,改进后的方案既能保证安全性又不会降低签名和验证性能。因此,改进方案更具有实际应用价值。     

一种基于改进的BP网的公钥密码的破译方法

该文以RSA密码系统为实例介绍了公钥密码体制的基本原理和破译，研究了神经网络在RSA密码体系中的应用，并给出了用BP神经网络来对公钥密码进行破译的基本结构及其学习算法，分析了用BP神经网络破译RsA密码的破译原理．给出了改进的BP网络模型及其学习算法，进行了仿真试验，在此基础上对构建的BP神经网络破译器的的结构进行了进一步的优化和改进，并给出了改进后的学习算法，最后对设计方法阐述了改进的必要性，试验表明方法的有效性和可行性。     

RSA系列算法在工程中的应用研究

网络安全产品中,大都需要使用密码算法。公开密钥算法主要有RSA和ECC等。本文根据工程应用的实际情况,对RSA系列算法进行了深入研究,分析了不同子算法的优劣,从中选出了适合工程应用的子算法,并结合我们的项目需求提出了一些对算法的改进。     

基于RSA算法的数字签名技术在电子商务中的应用

介绍数字签名在电子商务中的重要作用，探讨RSA算法的可行性和在数字签名中的应用，对RSA算法的安全性进行分析。     

RSA模乘器硬件优化设计

在分析RSA算法的基础上，着重对核心的模乘运算进行了优化，并在FPGA上对改进后的模乘算法以及1024位的RSA密码算法进行了仿真。实验结果表明，优化效果较为理想。本文涉及RSA模乘器能够较好地满足现代电子政（商）务，变电站远程通讯等应用系统的实时性要求，具有良好的应用前景。     

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.