Packet track and traceback mechanism against denial of service attacks

The denial of service attack is a main type of threat on the Internet today. On the basis of path identification （Pi） and Internet control message protocol （ICMP） traceback （iTrace） methods, a packet track and traceback mechanism is proposed, which features rapid response and high accuracy. In this scheme, routers apply packet marking scheme and send traceback messages, which enables the victim to design the path tree in peace time. During attack times the victim can trace attackers back within the path tree and perform rapid packet filtering using the marking in each packet. Traceback messages overcome Pi＇s limitation, wherein too much path information is lost in path identifiers; whereas path identifiers can be used to expedite the design of the path-tree, which reduces the high overhead in iTrace. Therefore, our scheme not only synthesizes the advantages but also compromises the disadvantages of the above two methods. Simulation results with NS-2 show the validity of our scheme.     

数字水印的高通块替换攻击

To improve the watermark benchmarks database, a new BRA (Block Replacement Attack) method is introduced in this paper. Unlike the typical BRA which exploits the self similarity among blocks in image, the scheme utilizes the self similarity in various scale and orientation bands in the wavelet domain of the image. They search the replacement blocks from the blocks of the smaller sub image at the next lower resolution. The most important advantage of this scheme is that the pyramid sub band decomposition acts as an automatic block classifier, with the result of simplifying the block search and block matching procedures and thus making the block replacement more effective. Furthermore, an improved algorithm based on Fuzzy set theory is introduced in which the number of blocks chosen for combination are modified adaptively to obtain the candidate replacement blocks. It simplifies the procedure for searching the candidate replacement blocks. These advantages are confirmed by the experimental results, which show that the performance of the scheme is superior to typical BRA methods.     

现阶段战场网络对抗总体发展建议

提议以网络中心战为背景构建网络对抗作战体系和效能评估体系。建议以"比特战"为切入点,引导现有通信对抗技术融合进入网络对抗技术体系,并以软件无线电和认知无线电为基础,发展网络对抗通用平台和系统,并兼顾专用平台和系统。由于"网络空间"的出现,战场网络对抗必然需要深入到网络内部,建议针对网络的开放性、复杂性和标准性,开展渗透攻击研究。     

面向机器学习模型的基于PCA的成员推理攻击

针对目前黑盒成员推理攻击存在的访问受限失效问题,提出基于主成分分析(PCA)的成员推理攻击.首先,针对黑盒成员推理攻击存在的访问受限问题,提出一种快速决策成员推理攻击fast-attack.在基于距离符号梯度获取扰动样本的基础上将扰动难度映射到距离范畴来进行成员推理.其次,针对快速决策成员推理攻击存在的低迁移率问题,提...     

基于输出频谱和支持向量机的模拟电路故障诊断方法

针对模拟电路的特点和其故障诊断中存在的问题,提出了一种基于输出频谱和支持向量机的新型模拟电路故障诊断方法(FMSVM)。该方法采用多音信号作为模拟电路的激励信号,并用其输出频谱中的有限个频率点的幅值作为故障特征,采用多分类支持向量机(MSVM)进行故障模式判别,实现了模拟电路的故障诊断。实验结果表明,该故障诊断方法具有速度快、准确率高的特点,具有重要的实用价值。     

Application of the Combustion Method in a Closed Flask to the Lead Determination in Atmospheric Aerosols

Abstract

The destruction of the filter for metal determination in atmospheric aerosols is an important step in the analysis. Nowadays the decomposition of this kind of sample has not been completely solved, so it is interesting to study new methods for filter sample attack. In the present work the application of the combustion method in a closed flask for mixed cellulose esters filter decomposition for lead determination is proposed. For this purpose optimum operating conditions as stopper flask design, sample size, flask volume, shaking time and volume and concentration of absorbing solution are established, and accuracy and precision of the proposed method using AAS for the measurements is given. The results obtained by the closed flask combustion are compared with those found by wet attack with HNO₃. The method proposed is rapid, has low reagent contamination and no loss of lead by volatilization or by amalgamation occurs. This method shows an accuracy and a precision in good agreement with the standard method.     

低轮FOX分组密码的差分碰撞攻击

This paper presents a method for differential collision attack of reduced FOX block cipher based on 4-round distinguishing property. It can be used to attack 5, 6 and 7-round FOX64 and 5-round FOX128. Our attack has a precomputation phase, but it can be obtained before attack and computed once for all. This attack on the reduced to 4-round FOX64 requires only 7 chosen plaintexts, and performs 242 .84-round FOX64 encryptions. It could be extended to 5 (6, 7)-round FOX64 by a key exhaustive search behind the fourth round. The time complexities of 5, 6 and 7-round FOX64 are approximate to 2106 .8, 2170 .8and 2234 .8, respectively. The attack on reduced FOX128 demands 11 chosen plain-texts, requires 2192one round encryptions in precomputation, performs approximately 276 .5 one round encryptions on 4-round FOX128, and is 2204 .5against 5-round FOX128.     

基于单变量多项式表示的具有最大代数免疫度奇变元函数构造

To protect against algebraic attacks, a high algebraic immunity is now an important criterion for Boolean functions used in stream ciphers. In this paper, a new method based on a univariate polynomial representation of Boolean functions is proposed. The proposed method is used to construct Boolean functions with an odd number of variables and with maximum algebraic immunity. We also discuss the nonlinearity of the constructed functions. Moreover, a lower bound is determined for the number of Boolean functions with maximum algebraic immunity.     

应急广播系统消息防重放攻击设计

应急广播是政府及相关部门向公众提供紧急信息的一种手段,是国家应急体系和国家公共服务体系的重要组成部分。我国的应急广播系统除了发布预警信息之外,还承担着政策宣传和舆论引导的职责,尤其是在边疆少数民族地区,承担了维护社会稳定的重要职能。因此,应急广播系统的传输安全、信息完整性的保护尤为重要。针对广播系统的业务特点以及广播领域常见的攻击破坏方式,提出了一种适用于各类应急广播传输通道的保护方式,可以有效抵御重放攻击方式。     

Convolutional Neural Network Approach for Multispectral Facial Presentation Attack Detection in Automated Border Control Systems

Automated border control systems are the first critical infrastructure point when crossing a border country. Crossing border lines for unauthorized passengers is a high security risk to any country. This paper presents a multispectral analysis of presentation attack detection for facial biometrics using the learned features from a convolutional neural network. Three sensors are considered to design and develop a new database that is composed of visible (VIS), near-infrared (NIR), and thermal images. Most studies are based on laboratory or ideal conditions-controlled environments. However, in a real scenario, a subject’s situation is completely modified due to diverse physiological conditions, such as stress, temperature changes, sweating, and increased blood pressure. For this reason, the added value of this study is that this database was acquired in situ. The attacks considered were printed, masked, and displayed images. In addition, five classifiers were used to detect the presentation attack. Note that thermal sensors provide better performance than other solutions. The results present better outputs when all sensors are used together, regardless of whether classifier or feature-level fusion is considered. Finally, classifiers such as KNN or SVM show high performance and low computational level.