ATLAS2000-Atlases of the future on the Internet

In geography new measuring techniques and imaging modalities have led to a huge amount of distributed data requiring new digital processing techniques. Environmental monitoring programs and analysis of global change in geography, meteorology, and climatology require an interdisciplinary usage of knowledge about the ecological system earth. Until recently the traditional atlas has been the primary tool for collection and dissemination of geographical knowledge about the earth. To advance the concepts of the atlas it is necessary to work on a methodological base different from that discussed before under the slogan digital atlas. The new tools that are developed in this project will permit an interactive, individual, and problem-related representation, the combination, modeling, and the interchange of multi-dimensional spatial and temporal data sets. A number of theoretical and practical aspects will be addressed, e.g., the investigation and interpolation of the space-time-continuum, the interpretation of data using different scales, and the use of subject-specific models for representation of measured and simulated data. Within the scope of the project some goals are in the fields of the development of hierarchical methods for compression, visualization and data access, thus enabling efficient handling of distributed resources in worldwide data and computer networks. Another task of the project lies in the development of didactical concepts for digital use of scientific data and models by a wide class of users. The project is a joint venture of the Institute for Physical Geography at the University of Freiburg and the Institute of Computer Science at the University of Leipzig.     

Proposed future Internet

The performance and reliability of a proposed future Internet—wired and wireless—is compared with the present Internet. Models of data transfer and queuing dynamics are used to make the performance comparison. These models consist of logic diagrams that express the sequence of data transfers in the Internet (e.g., local network to local network router) and queuing logic diagrams, supported by queuing equations (e.g., probability of local network queue busy). These models represent the steady state behavior of the present and proposed future Internets. C++ programs are used to simulate the variability in queue behavior. The results are used to identify the major variables in Internet performance (e.g., Internet routing time as a major performance variable). Furthermore, the results are used to compare present Internet and proposed future Internet performance. Reliability analysis is performed by predicting cumulative Internet faults and failures and by analyzing the complexity of present and proposed Internet configurations as an indicator of reliability (i.e., number of points of failure in a configuration). Model results demonstrate significant increases in performance and reliability for the proposed Internet, attributed to the elimination of data transfer overhead (e.g., elimination of Domain Name Service) and simplified network configurations.     

The Internet: global information superhighway for the future

The information revolution is bringing people of different backgrounds from around the world into a global information superhighway. The Internet provides a global platform connecting thousands of networks around the world. There is a variety of information available on the Internet for the users. It has been considered as a forum for users to share worldwide information resources. The resources are so vast that many of us really cannot grasp or understand the Internet fully. It has become a ‘global information library’ which allows the users to participate in the group discussion, search for any information, start any discussion with others and so on. It can be considered as a hybrid environment of postal services, citizen's band radio, libraries and neighborhood community centers where we (‘we’ is mainly used in this paper in its generic form) can spend time with our friends (‘our’ is also mainly used generically). Internet users (Internauts) share jokes, gossip in on-line conferences and join special groups to keep abreast of their specific interests. The main objective of this tutorial is to discuss various services on the Internet, their implementations, various Internet tools, and interconnection to the Internet. Other important issues like the Internet addressing, domain name system, IP addressing, etc. are discussed in detail in order to understand some design concepts. A brief list of the different types of browsers for different platforms is given. A discussion on future of the Internet is given via different advances and tools defined to provide security, interconnectivity and other related issues.     

基于PGP系统的电子邮件安全机制的实现

为了保障电子邮件在传输中的安全性,介绍了PGP系统所采用的加密算法及认证机制,简要介绍了利用PGP系统实现在发送方对电子邮件的加密以及签名,在接收方对电子邮件的发送方进行验证以及对密文进行解密。     

面向服务的未来互联网服务迁移机制

研究了基于传统互联网架构、覆盖网技术的现有服务迁移技术,解决了网络拥塞问题.现有服务迁移技术存在网络不可达、额外交互流量大和服务响应效率低的不足,结合网络用户行为和服务类别的特点,提出了基于服务计算的未来互联网体系结构的服务迁移触发策略,以及静、动态服务迁移算法,并在搭建的原型系统上对算法进行了测试.测试结果表明,这两种算法在降低骨干网服务请求流量的同时,能够明显提高服务迁移效率.     

Philip Zimmermann on What's Next after PGP

Will zFone—a new encryption program for voice-over-IP (VoIP) phone calls—do for VoIP what Pretty Good Privacy (PGP) did for email? Philip Zimmermann believes it can.     

PGP信任模型的改进

通过对PGP信任模型的分析，发现PGP信任模型具有以下缺陷：信任链长度太短，不利于信任的传播；推荐者在推荐公钥时只有信任和不信任两个等级；衡量信任度时只有少数几个离散的等级，粒度不够。针对以上这些缺陷，对其模型做了一些改进，但不可否认，在克服以上缺陷的同时模型的复杂度有所增加。     

PGP电子邮件系统的安全性分析及其改进

电子邮件是Internet上应用最广泛的服务之一,有个人信件的交换,也有重要商务信函的往来,所以电子邮件安全问题成为目前关注的焦点。该文分析了一种基于PGP的安全电子邮件系统的原理和安全性,研究和实现了基于椭圆曲线密码体制的安全电子邮件解决方案,有效地解决了邮件的安全问题。     

Mobile IPv6 and the future of wireless Internet access

Wireless technology is increasingly being used for Internet access and other IP-based communications. To make it easier for wireless users to exploit this trend, the Internet Engineering Task Force (IETF) designed Mobile IP version 4 in 1996. However, MIPv4 has not been deployed widely enough to provide much mobility and has several major shortcomings, including a cumbersome communications process and a limited number of IP addresses. The latter is a key problem because the number of mobile devices that need their own IP address to access the Internet is increasing rapidly. To overcome these deficiencies and introduce new capabilities, the IETF has been developing MIPv6. MIPv6 makes many more IP addresses available and lets mobile users stay connected to the Internet as they move between networks. The paper discusses MIPv6 implementation.     

As we may think-revisited [the future of the Internet]

With the approach of the 21st Century, computer and software technologies have changed the very fabric of our society. Beyond the sheer advances in processor speed, the most dramatic, far-reaching changes have occurred in the way we transfer information. Through the medium of the Internet, information can now be transmitted instantaneously from one end of the planet to the other. The future of information technology is bright, to be sure, but not without its challenges. For the Internet to enable us to achieve all our goals, it must gain a real-time context of who we are, our state and what we are doing. To this end, we must decouple context from the GUI and move it into a system built to hold it: a context engine. This system will let each of us organize our information according to the way we think, by association     

PGP信任模型的改进

通过对PGP信任模型的分析,发现PGP信任模型具有以下缺陷:信任链长度太短,不利于信任的传播;推荐者在推荐公钥时只有信任和不信任两个等级;衡量信任度时只有少数几个离散的等级,粒度不够。针对以上这些缺陷,对其模型做了一些改进,但不可否认,在克服以上缺陷的同时模型的复杂度有所增加。     

基于互联网基础的物联网安全问题

对物联网所面临的安全问题进行了分析和总结。针对物联网中存在的各种问题进行了深入研究,希望在发展物联网的同时,首先要重视其安全问题。     

关于PGP安全性的讨论

PGP是一个基于RSA公匙加密体系的邮件加密软件,它是一个杂合算法,本文从它所使用的几种算法入手,通过对这几种算法安全性的论述,使用户知道哪些因素会降低PGP的安全性,以及在使用中如何避免它们,以便提高邮件的安全性。     

基于Hide4PGP二次嵌入的音频隐写分析

针对隐写软件Hide4PGP隐写自相关性进行研究,以隐写一次与未隐写音频和隐写一次与隐写两次音频梯度能量的变化量,和将上述音频样本三级小波分解后,各级小波域细节分量线性预测误差的统计量（均值、方差、偏度和峰度）的变化量为特征向量,用支持向量机作分类器进行音频隐写分析。实验表明,这组特征可以有效地检测出经隐写软件Hide4PGP隐写的音频文件。在保持有效的检测率前提下,降低了特征维数,缩短了SVM分类时间,是对H.Farid所提特征的改进。     

PGP工作原理及其安全性

该文介绍了PGP系统的核心算法和工作流程。从加密算法、密钥管理、信任模型等几方面,探讨了PGP的安全性,并给出解决的办法。