一种安全性增强的Tor匿名通信系统

网络用户对自身隐私信息保护意识的增强,促进了Tor,Crowds,Anonymizer等匿名通信系统的发展及广泛应用,从而为用户提供了隐私和信息安全保护.随着对匿名通信系统的深入研究,发现部分系统存在安全性不足,为提高Tor匿名通信系统的安全性,基于可信计算技术提出一种安全性增强的Tor匿名通信系统,改进后的系统提高了目录服务器的安全性,并基于可信计算技术确保了用户及匿名通信链路的可信性;通过与Tor匿名通信系统的比较,改进系统在具有可信性的同时,具有更高的安全性及抗攻击能力,解决了Tor匿名通信系统所存在的安全隐患;通过仿真分析可知,改进后的系统能够满足用户的匿名性需求.     

Tor匿名通信流量在线识别方法

匿名通信技术的滥用给网络监管带来了新的挑战.有效识别出匿名通信流量,是阻止该类技术滥用的前提,具有重要的研究意义和应用价值.现有研究工作侧重于匿名通信关系的确认,无法用于匿名通信流量的识别和阻塞.针对这个问题,围绕广泛使用的Tor匿名通信系统,深入分析运行机制,归纳总结其流量特征.在此基础上,分别提出基于TLS指纹和基于报文长度分布的Tor匿名通信流量识别方法.对两种识别方法的优缺点和适用性进行了详细分析和讨论,并通过CAIDA数据集和在线部署对识别方法进行了验证.实验结果表明,基于TLS指纹和基于报文长度分布的识别方法均能有效识别出Tor匿名通信流量.     

第二代洋葱头路由匿名通信系统-Tor

Tor网络是目前Internet中最成功的公共匿名通信服务。首先简要概述了匿名通信和Tor网络的基本原理洋葱头路由。然后从三个方面对Tor网络进行了详细的阐述,具体为:Tor协议阐述了Tor的传输单元、通道构建机制和应有数据流传输机制;Tor网络的现状阐述了Tor网络目前的状态,包括用户和节点的分布情况,使用Tor网络服务的应用层协议情况和Tor网络的滥用情况;Tor未来发展面临的挑战,包括系统可用性的挑战、系统信誉度的挑战和系统抗滥用能力的挑战。     

匿名通信综述

匿名通信是网络与通信领域的热门课题。首先描述了匿名通信的起源,并从匿名属性、对手能力和网络类型三个方面对匿名通信的基本框架进行了阐述。然后阐述了匿名通信的研究现状,并对若干具有代表性的匿名通信系统进行了简要描述,匿名通信系统包括Anonymizer、Tor、Mixminion、Crowds和Tarzan。最后提出了匿名通信发展面临的挑战,包括匿名通信系统的用户体验、中继节点的信誉评价体系和匿名通信系统的滥用行为。     

基于深度森林的网络匿名流量检测方法研究与应用

网络流量分类一直是许多研究工作的关注领域,数据加密的普遍使用使其成为一个公开的技术挑战。数据加密是各种隐私增强工具中使用的一项关键技术。其中,基于匿名通信系统Tor构建的暗网是现今规模最大的匿名通信实体,常被犯罪分子用来从事各类违法犯罪活动,因此高效识别Tor流量具有重要研究意义。文章根据Tor匿名通信流量特点设计了一组用于Tor流量行为检测的网络流特征,并在原有深度森林模型的内存需求和时间开销局限性问题上,提出一种改进的深度森林模型,用于Tor网络流量的识别。实验结果表明,与已有识别方法相比,文章提出的模型准确率可达99.86%,同时,检测时间开销和内存需求都有所优化。     

洋葱路由追踪技术中时间特征的建模与分析

针对洋葱路由匿名通信机制,现有研究工作提出了多种基于时间特征的追踪技术方案,但对如何从理论上解释时间特征可用于追踪的原因,以及如何确定为形成特定时间特征所需调制的报文延时幅度等问题缺乏相应研究.以目前广泛使用的第二代洋葱路由Tor匿名通信系统为研究对象,深入分析其数据包调度策略,建立相应数学模型,并提出数据包输入和输出缓冲区的平均队列长度和网络层报文数量估算方法.在此基础上,结合提出的时间特征差异度度量方法,解释说明能够借助时间特征来进行匿名通信追踪的原因,同时得出影响追踪效果的3个具体因素.进一步,针对ON/OFF流水印模型,推导出在满足一定水印检测率前提下应调制的报文延时幅度.通过Tor实验环境验证了理论分析的正确性.研究成果为后续匿名通信相关研究提供理论和实践指导.     

匿名网络Tor与I2P的比较研究

Tor（the onion router）是部署最多的匿名通信系统,提供在线匿名和隐私保护,而隐形互联网I2P （invisible Internet project）允许应用程序通过使用大蒜路由,以匿名和安全方式相互发送消息。匿名网络Tor和I2P目前已受到学术界、工业界的高度重视,也受到用户的欢迎。网络Tor和I2P之间的设计理念区别关键在于：I2P试图将现有的互联网服务转移到I2P网络,并在框架内提供服务实现,而Tor则允许匿名访问分别实施和操作外部互联网服务。对匿名网络Tor、I2P分别从使用术语、项目开发、匿名服务、关键技术、威胁类型等多个方面进行比较,揭示两种匿名网络的内在联系与本质区别。     

基于网络行为匿名特征的Tor网络匿名度分析

Tor网络能够提供高质量的匿名服务,目前关于Tor网络匿名度研究主要是从系统设计的角度出发、基于信息熵理论构建静态匿名度模型,这类模型难以动态刻画Tor网络在不同网络环境下的具体网络行为的匿名性,因此本文提出了一种基于网络主体行为匿名特征的动态匿名度模型,改善了现存的匿名度表示方式不适用于大规模匿名网络的情况,并通过增加多种匿名特征的考量提升了匿名度的精确度,为匿名用户对匿名网络的匿名性评估提供理论依据,在此基础上,以Tor网络中常见的拥塞溯源为例,分析了Tor网络在恶意服务器发送爆发式流量拥塞匿名路径并以此特征进行溯源的复杂网络环境下的匿名度。     

通信技术在电子商务中的应用

随着Internet的迅猛发展和广泛应用,网上的匿名和隐私等安全问题也逐步成为全球共同关注的焦点,尤其在电子商务领域。文章从匿名通信技术的概述入手,简要论述了洋葱路由Tor匿名通信技术及其在电子商务中的应用。     

基于ARF的Tor网站指纹识别技术

不法分子通过Tor等匿名通信系统构建暗网隐匿其不法行为,给网络监管带来了严峻挑战.网站指纹识别技术能根据加密流量来推测用户访问的站点,是一种有效的监管手段.已有的网站指纹识别技术采用的多为基于批处理的静态模型,无法有效解决概念漂移问题.针对Tor网站指纹,文章提出一种基于自适应随机森林(ARF)算法的动态网站指纹识别模...     

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.