一种透明邮件过滤模型研究与实现

垃圾邮件的猖獗对反垃圾邮件技术提出了更高的要求。目前反垃圾邮件网关模型单一，可扩展性和跨平台性都比较差。本文针对这种情况提出了一种透明的反垃圾邮件网关模型。这种模型与企业网络的邮件服务器相互独立。而且它能够有效的利用目前以及将来出现的反垃圾邮件技术，具有良好的可扩展性。文章首先介绍了邮件以及反垃圾邮件技术，然后介绍了这种透明模型的实现，并分析了其性能上的优势与弱点，最后提出了在将来工作中需要进一步加强研究的方面。     

垃圾邮件过滤技术

电子邮件已经成为人们日常生活中通信、交流的重要手段之一,但垃圾邮件问题也日益严峻,网民平均每天收到的垃圾邮件数量已超过了正常邮件.因此目前反垃圾邮件技术的研究成为了一个热门的话题.文中介绍了基于安全认证、规则匹配和统计学习三类邮件过滤技术及应用情况,分析了过滤技术面临的挑战并指出垃圾邮件过滤的发展趋势.     

基于混合高斯模型的电子邮件多过滤器融合方法

本文提出了一种基于混合高斯模型(GMM)的多贝叶斯过滤器融合方法,并成功应用于电子邮件过滤.该方法使用多元统计分析方法对多个过滤器在训练例上的过滤表现矩阵进行降维和除噪,得到训练数据及各过滤器的分布;然后,从这一分布中学习出对邮件进行类别判定的GMM.GMM根据期望代价最小准则进行过滤,避免将正常邮件判定为垃圾.实验结果表明,本文方法具有较好的过滤性能,且对于特征提取率的敏感度低.     

反垃圾邮件过滤技术探讨

首先分析了垃圾邮件在我国泛滥的严重性，然后列举了现今被广泛使用的反垃圾邮件过滤技术，并重点分析了贝叶斯过滤技术在反垃圾邮件实践中的应用，最后对未来反垃圾邮件过滤技术提出了展望。     

基于贝叶斯定理的垃圾邮件分类技术研究

邮件过滤技术是反垃圾邮件的重要手段,目前对垃圾邮件的过滤主要有基于内容、基于IP地址和基于信头、信封等方法,这些方法对垃圾邮件的过滤起到了一定作用.但是由于信体是垃圾邮件的最终载体,而仅依据IP地址、信头、信封中的特征容易造成错误判断.在贝叶斯分类器的工作原理的基础上,提出了基于贝叶斯分类器的反垃圾邮件模型的原理与实现方法,将反映垃圾邮件的特征综合在一起统称为"属性",避免了单纯基于IP、信头、信封过滤的规则性太强的缺点,降低将正常邮件判断为垃圾邮件的风险.     

Infoglut

Information overload isn't just about having too much e-mail, voice mail, and text messages. It's a much more complex problem, and its effects take a toll on companies' bottom lines and on their employees' well-being. The time that information workers invest in coping with this overload is significant; at Intel, where I was until recently a principal engineer, we assessed the loss due to unnecessary e-mails and unproductive interruptions at 8 hours a week. In a 1996 Reuters survey of 1300 managers worldwide, two out of three respondents associated information overload with loss of job satisfaction and tension with colleagues, and 42 percent attributed ill health to this stress. Today, more than 10 years later, the numbers would likely be even higher.     

Securing your Internet connection: a sequel

This author discusses the problem of Internet security. He draws some parallels between spammers trying to trick victims to opt out of their e-mail list in order to obtain information on valid e-mail addresses with so-called social engineering techniques used by security perpetrators. The term social engineering is typically used to describe a human-interactive (the emphasis is on the word human as opposed to computer-based) process that tricks people into violating security policies and procedures to get unauthorized access to protected information exposing security vulnerabilities. The best way to deal with social engineering threats is through creating and enforcing strict security procedures through education and training     

基于贝叶斯方法的客户端邮件过滤器的设计与实现

伴随着电子邮件的广泛使用,垃圾邮件泛滥成灾,严重影响了人们正常的学习、工作和生活。本文通过对垃圾邮件的分析与处理,设计并实现了基于贝叶斯方法的客户端邮件过滤系统。实验证明贝叶斯方法能够有效的过滤垃圾邮件。     

Research of Anti-spam System Basing on Immunity System and Mobile Agent

The human immune system has the function of self- discern. It can identify the non - self antigen and clear it through the immune response automatically. So, human body has the power of resisting disease. The anti - spare system basing on immune system is proposed by using immune system＇s theory,and it is introduced in the mail service of enterprise VPN. Regard VPN as the human body, the mobile agent is simulated the antibody because of its movable and intelligent, and the spare is simulated the antigen. It can clear the spare by using immune mechanism. This method is a new thinking of anti - spare mail. The advantage is overcoming the weakness on independence of traditional anti - spare system.     

IM means business

Instant messaging (IM), no longer just a facet of teenage life, now speeds everything from naval operations to customer service. IM is moving from computers and laptops to cellphones, PDAs, and other devices. Through its prosaic "buddy list," a continuously updated window that shows who among your family, friends, or colleagues are online and available, IM connects you to your inner circle in ways that phones and e-mail can't. What will make IM more than just the next hot idea to come and go is a single key feature called presence. In essence, this is a protocol to tell the world that you're available on a particular device. Outside IM, presence is being built into collaboration tools, word processors, e-mail directories, and even online games. Being always available has its drawbacks, of course. All too often, work and other obligations spill over into our private time. Many find the prospect of co-workers and even family always being able to contact us daunting. Concentration can be shattered; questions that seem important to the questioner may not be so to you. If usability researchers and application developers get it wrong, presence will be a burden, instead of a benefit. If they get it right, though, if they can deliver the right amount of your availability to the right set of people, IM can become the main way we initiate contact with the people we communicate with most often. indeed, those now-primary forms of communication, the telephone and e-mail, will either have presence built into them, or take a back seat to IM.     

反垃圾邮件网关技术的标准进展

随着互联网的高速发展,反垃圾邮件网关已经成为阻止垃圾邮件日益泛滥的有力武器。本文介绍了反垃圾邮件网关的技术现状及其标准的进展情况。     

Efficient searchable ID-based encryption with a designated server

Public key encryption with keyword search (PEKS) is a mechanism that allows one to extract e-mails containing a particular keyword by providing a trapdoor corresponding to the keyword. And parties without the trapdoor are unable to learn any information about the extracted e-mails. Meanwhile, a PEKS scheme is also suitable to provide a secure storage system in cloud computing environment. However, in a PEKS scheme, a secure channel must be established to transmit trapdoors. A PEKS scheme with a designated server, termed dPEKS, removes the requirement of the secure channel while retaining the same functionality of PEKS. Up to date, the related studies on dPEKS are all based on the pairing-based public key system. No work focuses on dPEKS based on ID-based systems, termed dIBEKS. In this article, we propose the first dIBEKS scheme that possesses the advantage (removing certificate management) of ID-based systems. Security analysis is given to demonstrate that our scheme is provably secure and can resist off-line keyword guessing attacks. When compared with previously proposed dPEKS schemes, our scheme has better performance in terms of computational time.     

电子邮票系统的设计与改进

垃圾邮件日益泛滥,严重损害了互联网服务提供商和消费者的利益。介绍了现有的反垃圾邮件的技术发展与现状,在分析电子邮票系统设计的基础上,提出了一种基于分布式的信誉度管理进行垃圾邮件防护的方法。同时,针对信誉度方法,给出了新的系统信誉层次结构的具体框架和实现垃圾邮件防护的过程。理论和实验结果表明：该方法可以有效地提高邮件的误判率,从而弥补了基于发送许可的邮件验证系统所产生的缺陷。     

最小风险的Naive Bayes技术在反垃圾邮件系统中的应用

文章提出了一套更好地过滤中文垃圾邮件的方案，这套方案将利用垃圾邮件规律的规则过滤和最小风险的Naive Bayes内容过滤算法结合了起来，并根据垃圾邮件的特性做了必要的改进。并且这套方案也在Linux／Solaris系统平台下基本上完成了大部分功能的软件编程。实际电子邮件服务器上对本方案进行了测试．结果显示这套方案取得了很好的过滤效果。最小风险的Naive Bayes技术是目前最重要的反垃圾邮件技术之一。     

BURSTS: A bottom-up approach for robust spotting of texts in scenes

In this paper, we present a bottom-up approach for robust spotting of texts in scenes. In the proposed technique, character candidates are first detected using our proposed character detector, which leverages on the strengths of an Extremal Region (ER) detector and an Aggregate Channel Feature (ACF) detector for high character detection recall. The real characters are then identified by using a novel convolutional neural network (CNN) filter for high character detection precision. A hierarchical clustering algorithm is designed which combines multiple visual and geometrical features to group characters into word proposal regions for word recognition. The proposed technique has been evaluated on several scene text spotting datasets and experiments show superior spotting performance.     

高校误判垃圾邮件自动召回系统的研究与实现

垃圾邮件的误判问题一直是反垃圾邮件领域中未能得到根本解决的难点。基于清华大学邮箱系统及反垃圾邮件网关系统进行了一整年的部署和实验（2011年9月至2012年10月）,通过用户对可疑垃圾邮件点击召回的历史行为进行分析,并采用对其感兴趣的垃圾邮件进行文本相似度计算以及关键参数预测的方法来智能化预测用户对当前某一封垃圾邮件的感兴趣程度,即基于用户主观的选择和体验来帮助用户自动召回其可能感兴趣、然而却被反垃圾邮件网关误判的垃圾邮件,解决了传统过滤方法无法杜绝误判的问题。     

Spam: One Pozzled Problem for E-Commerce

E-commerce has advantages of low bargaining cost, full field service, and convenient. Its development forms and promotes the key factor of the global economic growth, and the security problem of e-commerce becomes more and more important thereupon. It is the subject of a great meaning to structure the safe, convenient e-commerce running environment. The task of anti-spam is a concrete content among them. This paper discusses the source and danger of spam, and the precautionary and radical cure measures of spam are put forwarded, and the technologies of the anti-spam are discussed especially.     

Filtering spam from bad neighborhoods

One of the most annoying problems on the Internet is spam. To fight spam, many approaches have been proposed over the years. Most of these approaches involve scanning the entire contents of e-mail messages in an attempt to detect suspicious keywords and patterns. Although such approaches are relatively effective, they also show some disadvantages. Therefore an interesting question is whether it would be possible to effectively detect spam without analyzing the entire contents of e-mail messages. The contribution of this paper is to present an alternative spam detection approach, which relies solely on analyzing the origin (IP address) of e-mail messages, as well as possible links within the e-mail messages to websites (URIs). Compared to analyzing suspicious keywords and patterns, detection and analysis of URIs is relatively simple. The IP addresses and URIs are compared to various kinds of blacklists; a hit increases the probability of the message being spam. Although the idea of using blacklists is well known, the novel idea proposed within this paper is to introduce the concept of ‘bad neighborhoods’. To validate our approach, a prototype has been developed and tested on our university's mail server. The outcome was compared to SpamAssassin and mail server log files. The result of that comparison was that our prototype showed remarkably good detection capabilities (comparable to SpamAssassin), but puts only a small load on the mail server. Copyright © 2010 John Wiley & Sons, Ltd.     

基于用户需求垃圾邮件过滤分类模型设计

以朴素贝叶斯理论作为基石并结合信息增益、代价因子等方法,尝试设计一种基于用户需求的垃圾邮件过滤分类模型,在垃圾邮件一次分类基础上提出邮件先过滤后分类方法,进而改进传统邮件分类一次阈值比较,变为两次阈值比较,且应用反馈技术以应对垃圾邮件的日益变化.该模型可能会对垃圾邮件多分类研究具有一定的参考价值.     

一种基于结构优化的FIR滤波器舍入噪声性能改进方案

针对滤波器组系统硬件实现时原型滤波器的有限字长效应问题,该文研究如何改善FIR原型滤波器由信号量化引起的舍入噪声,即降低舍入噪声增益,提出一种FIR滤波器优化结构。通过分析舍入噪声来源,利用多项式参数化方法对舍入噪声增益表达式进行推导。仿真实例证明,在不同字长约束条件下所提结构滤波器的幅频相频响应与理想状态基本吻合;通过与现有算法对比,所提结构具有较小的舍入噪声增益。