DOS攻击原理及对策

随着互连网应用的推广普及,威胁网络可靠运行的安全问题变得极为重要.通过详细研究严重危害网络安全的DOS攻击,提出了预防并消除其破坏的具体方法和措施.     

Mlgebraic Attack on Filter-Combiner Model Keystream Generators

Algebraic attack was applied to attack Filter-Combiner model keystream generators. We proposed thetechnique of function composition to improve the model, and the improved model can resist the algebraic attack. A new criterion for designing Filter-Combiner model was also proposed: the total length L of Linear Finite State Machines used in the model should be large enough and the degree d of Filter-Combiner function should be approximate [L/2].     

数字水印的应用及攻击类型

随着多媒体技术的应用,在多媒体数据中嵌入隐蔽标记的数字水印技术,因其保真性、安全性和鲁棒性,在票据防伪、拷贝控制及广播监视等领域得到了探索性的应用.同时针对水印系统的攻击也越来越多,影响了水印的安全性.针对水印系统的攻击主要分为三大类:未经授权的删除、未经授权的嵌入、未经授权的检测.本文从水印系统的特性、应用、攻击三个方面对数字水印技术进行论述.     

利用双水印技术对抗解释攻击

数字水印是实现版权保护的有效办法,但到目前为止,尚没有一个算法能够真正经得住攻击者所有种类的攻击,其中以解释攻击最为危险。本文通过对解释攻击进行分析,重点介绍了利用双水印技术对抗解释攻击的方法。     

计算机网络安全与防御

目前,全世界军事、经济、社会、文化各方面都越来越依赖于计算机网络,人类社会对计算机网络的依赖度达到空前的记录。由于计算机网络极易受到攻击,这种高度依赖性使国家经济和国防安全变得十分“脆弱”。一旦计算机网络受到攻击, 不能正常工作,甚至全部瘫痪时,整个社会就会陷入危机。 1 计算机网络安全的现状据美国联邦调查局统计,美国每年因网络安全造成的损失高达75亿美元。据美国金融时报报道,世界上平均每 20分钟就发生一次入侵国际互联网络的计算机安全事件,1/3的防火墙被突破。美国联邦调查局计算机犯罪组负     

给现代武器“降温”红外隐身技术扫描

黑夜,伸手不见五指。广袤的沙漠上空,一架架“阿帕奇”攻击直升机呼啸而来。突然,直升机上挂载的“小牛”导弹从天而降,寂静的沙漠上瞬间掀起了一阵阵的爆炸旋风。直升机过后,一个个沙坑中出现的是一辆辆坦克的残骸。没有丝毫的对抗,沙层中的坦克简直就是这些直升机的训练靶标。这一幕,相信了解海湾战争进程的人们不会忘记。因为这就是当年伊拉克准备让美军“血流成河”的“萨达姆防线”悲剧。美军有绝对的空中优势,伊拉克有强大的地面兵力。为了防止空中打击,萨达姆将自己的3000多辆坦克全部埋在沙漠之中,只等着地面战事的到来。但萨达姆这…     

A Robust IP Packets Filtering Mechanism for Protecting Web Server from DDoS Attacks

Distributed denial of service （DDoS） attacks exploit the availability of Web servers, resulting in the severe loss of their connectivity. We present a robust IP packets filtering mechanism which combines the detection and filtering engine together to protect Web Servers from DDoS Attacks. The mechanism can detect DDoS attacks by inspecting inbound packets with an IP address database, and filter out lower priority IP addresses to preserve the connection for valid users by monitoring the queues status. We use the Netfilter＇s technique, a framework inside the Linux 2.4. X, to implement it on a Web server. Also, we evaluate this mechanism and analyze the influence of some important parameters on system performance. The experimental results show that this mechanism is effective against DDoS attacks.     

An Improved Model of Attack Probability Prediction System

This paper presents a novel probability generation algorithm to predict attacks from an insider who exploits known system vulnerabilities through executing authorized operations. It is different from most intrusion detection systems （IDSs） because these IDSs are inefficient to resolve threat from authorized insiders. To deter cracker activities, this paper introduces an improved structure of augmented attack tree and a notion of ＂minimal attack tree＂, and proposes a new generation algorithm of minimal attack tree. We can provide a quantitative approach to help system administrators make sound decision.     

Improved Authenticated Multi-Key Agreement Protocol

Zhou et al give an attack on Ham＇s modified authenticated multi-key agreement protocol, and give a protocol that can prevent the unknown key-share attack. The paper points out that the protocol is vulnerable to a concatenation attack. This paper proposes an improved authenticated multi-key agreement protocol which shows how to make Harn＇s protocol more secure by modifying the signature and verification. And this protocol can escape the concatenation attack.     

浅谈数字水印技术

数字水印是版权保护的重要手段,是当今的研究热点。本文对数字水印技术的基本工作原理、特性、分类进行了介绍,对典型攻击、典型算法及其应用领域进行了探讨和分析。