网络隐蔽通道检测系统模型设计

利用TCP／IP协议中建立隐蔽通道来进行非法通信已经成为网络安全的重要威胁。论文首先以IP协议和TCP协议为例,简要介绍了TCP／IP协议下网络隐蔽通道的建立方法和检测特点,针对目前检测工具主要面向特定隐蔽通道的特点,结合协议分析和流量分析方法提出了一种网络隐蔽通道检测系统的设计模型,为隐蔽通道的综合性检测提供了一种新的思路。     

泛在网络环境下隐蔽通道关键技术研究综述

在泛在网络环境下,隐蔽通道通过修改系统共享资源,绕开系统的安全策略传输隐蔽信息,给计算机和网络系统造成了严重的安全威胁.针对此问题,主要从度量、构建和检测3个方面对泛在网络环境下的隐蔽通道相关研究进行归纳和分析.首先,总结归纳了典型的隐蔽通道度量指标,包括隐蔽通道的容量、稳健性、抗检测性、规律性和形状.其次,归纳整理了...     

安全操作系统中隐蔽通道的研究

安全操作系统是信息系统安全的基础,隐蔽通道是解决操作系统安全的瓶颈。论文首先介绍了一种对隐蔽存储通道进行细分的方法,即把隐蔽存储通道分为直接隐蔽存储通道和间接隐蔽存储通道。接着在对隐蔽通道进一步分析的基础上,给出了隐蔽通道产生的充要条件。     

基于DNS的隐蔽通道流量检测

为提出一种有效检测各类型DNS隐蔽通道的方法,研究了DNS隐蔽通信流量特性,提取可区分合法查询与隐蔽通信的12个数据分组特征,利用机器学习的分类器对其会话统计特性进行判别。实验表明,决策树模型可检测训练中全部22种DNS隐蔽通道,并可识别未经训练的新型隐蔽通道。系统在校园网流量实际部署中成功检出多个DNS隧道的存在。     

隐蔽通道的信息传递模型

隐蔽通道的存在给信息系统的保密性造成了严重威胁,其信息传递机理研究是实施隐蔽通道检测与控制的前提和基础．本文首先将安全系统解释成带有信号调制能力的通信信道,将信息传递过程类比成常规通信过程,研究了相应的通信要素（编码器、调制器、载波介质及解码器等）及其所对应的实体;基于这些通信要素和对应实体,提出了隐蔽通道的信息传递模型;在该模型和系统形式化描述的基础上,研究机密信息泄露的过程,并讨论了隐蔽通道的信道带宽计算方法．     

隐蔽通道在Web Service 调用中的应用研究

目前,在基于.NET开发环境下,Web Service技术日渐得到广泛应用.随之而来的信息安全成为在信息通信中首要考虑的问题.在已有的Web Service技术应用基础上,对隐蔽通道的相关问题进行分析研究,针对Web Service技术的信息安全问题提出改进方案.以此提高应用Web Service技术的安全性和信息可靠性.     

AJAX技术下隐蔽通道的安全设计

通过Internet,在使用AJAX方式下载文件的代码中调整存储路径,会导致在文件下载进程中,存在隐蔽存储通道的问题,隐蔽通道的存在会给信息安全带来隐患。为提高下载信息的安全性和可靠性,通过分析隐蔽通道处理技术,对隐蔽通道的存在进行改进,并设计了一种安全模型,对下载的数据信息进行隐蔽存储通道的消除和过滤,通过MD5值验证下载信息的完整,为网络下载中确保信息数据的安全性和可信性提供保障。     

适应性随机延迟的网络隐蔽时间通信干扰方法

在网络隐蔽时间信道中,数据包的发送或到达时间被操控以携带消息而达到隐蔽传送信息的目的。这种信道的存在会对信息私密性带来危害,因此应该被干扰或加以限制。因为网络隐蔽时间信道寄生于正常通信信道,对它的干扰不可避免会对正常网络通信带来负面影响。论文提出了如何在多重限制条件下对网络隐蔽时间信道进行干扰的问题,并针对这一问题给出了基于适应性随机延迟的解决方案。     

网络数据通信中的隐蔽通道技术

随着科学技术的不断发展,网络技术也发生了日新月异的变化。文章通过对网络数据通信中的隐蔽通道技术的介绍,进一步就网络通信中隐蔽通道存在的技术基础和实现原理进行了探讨,并对网络通信隐蔽通道技术进行了深入的研究与分析。与此同时对隐蔽通道的检测技术进行了讨论,提出了一系列针对网络安全的防范措施。     

网络隐蔽通道及其识别技术研究

介绍网络隐蔽通道及其识别技术.在对网络隐蔽通道概念、原理和分类进行具体介绍的基础上,提出特征匹配、协议异常分析和行为异常分析三种隐蔽通道检测技术,并具体介绍了一个针对行为异常分析检测技术的典型应用.文中就网络隐蔽通道检测技术提出的三种手段相结合的思路具有较高的实用性和一定的创新性,已在实际应用中取得了较好的效果.     

Method of interference cancellation based on space-time code in MIMO interference channels

The authors in this article investigated how to cancel multi-user interference with low feedback amount over 3-user multiple input multiple output(MIMO) interference channel using space-time code and precoders. Space-time block code with coding rate 2 was designed, also zero vectors were introduced into each codeword. The multi-user interference is mitigated by pre-coding at the transmitters and nonlinear operation and unidirectional cooperation link at the receivers. Compared with the existing scheme for the same scene, the proposed scheme greatly reduces feedback amount and improves the sum degrees of freedom(DOF). Simulation demonstrates the validity of the proposed scheme.     

基于Matlab的劈尖干涉仿真

根据等厚干涉的基本理论,利用Matlab平台编程进行仿真,模拟劈尖干涉实验在不同参数条件下的光强分布情况。并用Matlab自带的Peaks函数模拟利用劈尖干涉对平面玻璃表面进行缺陷检测的干涉条纹。仿真所得到的干涉图像细致逼真,并且能够动态地反映出干涉条纹随参数的改变而发生变化的过程,使得物理规律形象直观。Matlab模拟出的干涉图像与实验结果非常吻合,还可以灵活地调节参数,大大扩展了劈尖干涉问题的研究途径与方法,有助于学生更加深刻地理解物理光学的现象和规律,也为光学的理论教学和实验方式提供了便利。     

Co-channel interference analysis of shadowed Rician channels

This paper presents an exact analysis of co-channel interference (CCI) in a shadowed-Nakagami (desired)/shadowed-Rician (interfering) channel. Because a Rician distribution can be closely approximated by a Nakagami distribution (Nakagami 1960), the proposed analysis can be viewed as a close approximation of a shadowed-Rician (desired)/shadowed-Rician (interfering) model. The model provided in this paper includes many flexibilities-different Rice factors, different shadowing spreads, and different transmitted powers for desired and interfering signals. Therefore, it is a powerful tool for determining cell sizes and power levels in mixed micro/macro cellular systems     

Dynamic analysis for covert channel based on grey relational analysis algorithm

Search and recognition is the most important part of the covert channel analysis. At present, most of the covert channel search methods are static analysis on system. It has many shortcomings, such as heavy workload, omission, inaccurate, and so on. It is necessary to find the dynamic search method for covert channel during a system is running. This paper presented a covert channel dynamic search method based on grey relational analysis algorithm (GRAA) in gray theory. The method is efficient and can be used in conjunction with existing covert channel search methods. Finally, a closed-loop feedback will be formed so that the system's safety mechanism can be self-improvement gradually.     

Design and analysis of low-complexity interference mitigation onvector channels

Linear multiuser detectors for vector channels with crosstalk are approximated by weighted matrix polynomials. The weight optimization problem is overcome using convergence results from random matrix theory. The results are also extended to receivers with subsequent successive decoding. In the case of subsequent successive decoding, a novel low-complexity implementation is found for the first-order approximation that is based on matched filter banks only and does not require matrix algebra. Spectral efficiency is obtained analytically and found to be fairly close to the optimum. The paper is focussed on multiuser detection for CDMA, but the results can be easily extended to communication via antenna arrays     

Exact cochannel interference analysis for log-normal shadowedRician fading channels

An exact analytical method is presented for evaluating the probability of cochannel interference for Rician/Rayleigh faded channels with log-normal shadowing. The method requires that at least one signal (desired or interfering) be Rayleigh faded and log-normal shadowed. The Rice factor of the desired signal is shown to have a large effect on the probability of cochannel interference, while the Rice factors of the interfering signals are shown to have little effect     

基于双缝干涉水导激光打孔的仿真研究

水导激光加工技术具有热效应小、精度高、无刀具损坏等优点,被应用到高精度元件的加工中。为减小激光聚焦光斑直径以利于激光与水射流的精确耦合、提高激光孔的质量,提出了基于双缝干涉原理以减小激光聚焦光斑直径的方法。构建了传统水导激光和双缝干涉水导激光打孔的几何模型和数学模型;基于COMSOL分别进行仿真,对比和分析了在激光束参数、加工条件均相同的条件下,传统水导激光和双缝干涉水导激光打孔时对激光孔轮廓的演化、热影响区域分布和重铸层大小的影响。结果表明:与传统水导激光相比,采用双缝干涉水导激光加工技术能有效地减小激光孔直径、锥角、热影响区域宽度和重铸层大小,在现有条件下进一步减小激光聚焦光斑直径。     

干扰信道中ZF协作MIMO发射的性能分析

针对有协作反馈的多输入多输出(MIMO, multiple-input multiple-output)干扰信道,研究了迫零(ZF, zero-forcing)协作发射策略的性能。为了推导和速率(sum rate)与中断概率等性能指标的解析表达式,研究了在MIMO 的维数趋向无穷时,各性能指标的渐近特性。利用随机矩阵理论,首次提出了迫零协作发射策略中等效矩阵所有特征值的一个渐近估计。并基于此推导了和速率的2个闭式表达式,同时还获得了和速率随着MIMO 维数变化的缩放律。此外,利用多元统计中Wishart矩阵最小特征值的概率分布函数的相关结论,推导了2种特例下的上述协作发射策略的中断概率表达式。仿真结果验证了所提的性能指标解析表达式不仅在大维的情况下成立,而且在中等维度下也是有效的。     

Performance analysis of covert wireless communication based on beam forming with noise uncertainty

In order to establish covert wireless communication in Rayleigh fading environment with noise uncertainty,a scheme of downlink covert wireless communication based on complex Gaussian random coding and beam forming was adopted,and more importantly,the performance of covert wireless communication was analysed.Firstly,the covert probability of communication was analyzed by using the hypothesis test theory.Secondly,the optimal detection threshold of the illegal detection party was given and proved,and the closed expressions of the average covert probability,connection interruption probability and covert throughput of the system were further obtained.Finally,by jointly designing the transmission power and target covert rate,the optimal goal of the maximum covert throughput of the system was achieved,and the corresponding algorithm based on step search was given.The simulation results show that the beam forming technology could provide some gain for covert wireless communication.Compared with the ideal case in which the legitimate receiver is not affected by the noise uncertainty,the covert throughput in non-ideal case is significantly reduced and almost not affected by the basic noise level of the environment.