基于依赖图的信息流图构建方法*

信息流分析法是一种有效的隐通道搜索方法,用信息流图来描述系统中信息流的流动情况。直接基于系统源代码生成系统信息流图,由于信息流的传递关系,会引进大量系统中不存在的信息流路径。利用程序依赖图先处理系统信息流中的传递关系,然后再进行信息流图的生成,从而减少引入系统中不存在的信息流路径,减少信息流分析时的工作量。     

隐蔽流树方法的分析与改进

利用隐蔽流树方法搜索隐蔽通道时,获得的操作序列中只有极少部分真正构成隐蔽通道,增加了后续手工分析的工作量。为此,提出一种改进的隐蔽流树方法。根据信息流图进行建树,设计信息流规则,并给出隐蔽流树的自动分析算法。以一个文件系统为例进行分析,结果验证了改进方法的正确性。     

结合非局部信息与图割的图像分割算法

基于图割的交互式图像分割方法从图像背景中分离出前景目标,在图像处理和计算机视觉领域引起了广泛的关注.为了进一步提高分割精度,提出一种结合图像非局部信息和图割的交互式图像分割算法.在建模图像非局部信息时为每个像素点设置一个固定大小的搜索窗口,每个像素点只需考虑与搜索窗口内像素之间的关系;计算非局部像素对之间相似性时采用图像片替代像素,通过图像片之间的相似性替代像素之间的相似性,以表征图像的非局部信息;将图像非局部信息引入到图割框架中,在传统能量函数的边界项将图像的局部信息与非局部信息合并,组成结合局部非局部信息的新的能量项;构图时新添加一组边集?非局部边集来表示图像的非局部信息,再通过最大流/最小割算法求解得到最终的分割结果.最后通过实验验证了该算法的有效性和可行性.     

融合模糊聚类的蚁群图像增强算法

为提高边缘检测精准度,保证图片分割后效率和效果,本文提出一种基于融合模糊聚类的蚁群图像增强算法。该算法利用分量灰度值、灰度梯度值和领域特征值进行图像特征提取,得到特征灰度图;然后使用模糊聚类算法对区域蚂蚁进行聚类以提高收敛速度;再采用蚁群算法进行图像边缘检测,检测过程中,使用路径选择策略对蚁群进行有序搜索,提高搜索效率,又根据信息素更新策略进行最优路径信息交流,以达到边缘点提取与检索目的;最后将检索所得灰度边缘图与原图进行重合,得到图像增强效果。实验结果表明,该改进算法在检索时间方面相较于传统蚁群算法提高了20.7%;在精度方面提高了14.8%,图片分割效果更好,纹理更清晰。     

基于源代码的隐通道搜索方法

针对目前隐通道搜索方法仍采用手工分析语句信息流所带来的工作量巨大问题,提出了一种基于源代码的信息流分析法,找出软件系统源代码中原语间兼具可见性和可修改性的共享变量,再以此作为共享资源矩阵法的输入,得到高效高精度的隐通道分析工具。     

基于多尺度的贝叶斯模型显著性检测

针对传统基于贝叶斯模型的显著性检测算法存在准确率不理想的问题,提出了一种基于多尺度的贝叶斯模型显著性检测算法。通过超像素分割算法(SLIC)将原图分割成不同尺度的超像素,根据超像素边界信息得到背景种子,进而通过距离计算和多尺度融合得到背景先验;对原图进行颜色增强,采用Harris算子对增强图进行检测角点求得凸包,融合不同尺度下的超像素得到凸包先验;融合背景先验和凸包先验得到最终先验;利用颜色直方图和凸包计算似然概率;将最终先验和似然概率通过贝叶斯模型计算显著图。在公开数据集MSRA1000、ECSSD上与多种传统算法进行准确率和召回率对比,该算法有更好的表现。     

利用有向环的性质求解可达关系

不确定规划研究的最终目标是求出规划解,但是由于缺少引导信息,直接求规划解会导致大量的无用状态和动作被搜索。获得状态间的可达关系可以避免冗余计算。目前求可达关系的方法效率较低,因此设计了一种求可达关系的新方法。将不确定状态转移系统抽象成一个图,在这个图中,查找状态之间的可达信息是否形成一个有向环。若存在一个有向环,说明环内每两个状态之间都有可达关系。将其中一个状态作为父节点,并且将这个环内所有状态的可达关系记录在父节点中,通过访问父节点的可达信息更新环内状态的可达信息,减少了许多无用的状态和动作被搜索。实验结果表明,所设计的算法不仅能得到更全面的可达关系,而且效率也高于已有的算法。     

基于图像分割的立体匹配算法

针对在立体匹配中弱纹理及纯色区域匹配不准确和图像分割算法耗时较多的问题,提出一种融合图像分割的立体匹配算法。首先,将初始图像进行高斯滤波和Sobel平滑的处理,获取图像的边缘特征图;然后,将原图的红、绿、蓝三个通道值采用最大类间方差法进行二分类,再融合得到分割模板图;最后,将所得到的灰度图、边缘特征图和分割模板图用于视差计算和视差优化的过程,计算得到视差图。相比绝对差值和(SAD)算法,所提算法在精度上平均提升了14.23个百分点,时间开销上平均每万个像素点只多消耗了7.16 ms。实验结果表明,该算法在纯色及弱纹理区域和视差不连续区域取得了更加平滑的匹配结果,在图像分割上能够自动计算阈值且能够较快地对图像进行分割。     

网络隐写信息传递系统的高效攻击检测

在网络隐写信息的攻击检测中,为了保护数据的隐私,需要加入大量伪装隐私对数据本质特征进行隐藏,使得被攻击后的攻击特征也被覆盖,导致特征淡化.传统的攻击检测几乎都是对固定攻击特征进行检测,无法检测隐写信息的安全.提出利用多层次加权模型的网络隐写信息传递系统攻击检测方法.搜索网络隐写信息传递中的可能攻击事件,针对搜集的攻击事件进行建模,获取信息隐藏状态下,遭受攻击的衡量标准,建立网络隐写信息传递系统攻击数据集合,得到攻击检测模型,实现网络隐写信息传递系统的攻击检测.实验结果表明,利用改进算法进行网络隐写信息传递系统的攻击检测,能够提高检测的准确性.     

面向时序图数据的快速环枚举算法

时序图数据是一类边上带有时间戳信息的图数据.在时序图数据中,时序环是边满足时间戳递增约束的回路.时序环枚举在现实中有着很多应用,它可以帮助挖掘金融网络中的欺诈行为.此外,研究时序环的数量对于刻画不同时序图的特性也有重要作用.基于2018年由Rohit Kumar等人提出的时序环枚举算法（2SCENT算法）,提出一种通过添加环路信息来削减搜索空间的新型时序环枚举算法.所提出的算法为一个两阶段的算法：1）首先,通过遍历原图获得所有可能会形成环路的节点,以及相应的时间和长度信息;2）然后,利用以上信息进行动态深度优先搜索,挖掘所有的满足约束条件的环.在4个不同的真实时序图数据集上进行了大规模的实验,并以2SCENT算法作为基准对算法进行了对比.实验结果表明,所提出的算法较之前最好的2SCENT算法要快50%以上.     

A technique to analyze information-flow in object-oriented programs

Traditional information-flow analysis is mainly based on data-flow and control-flow equations. In object-oriented programs, because of the mechanisms such as encapsulation, inheritance, and polymorphism, information-flow analysis becomes quite complex and therefore it is not enough to analyze object-oriented information-flow using traditional techniques. Some new techniques are required in order to efficiently analyze the information-flow between basic components (such as statements, methods, classes or packages) in object-oriented programs. Based on object-oriented program slicing techniques, we discuss how to compute the amount of information-flow, the width of information-flow, the correlation coefficient between basic components as well as degree of coupling of a basic component can be computed. We also discuss some applications of the information-flow.     

A uniform presentation of confidentiality properties

Security (in the sense of confidentiality) properties are properties of shared systems. A suitable model of shared systems, in which one can formally define the term security property and then proceed to catalog several security properties, is presented. The purpose is to present various information-flow properties in a manner that exposes their differences and similarities. Abstraction is the main tool, and everything that is not central to the purpose is discarded. The presentation is generic in the model of computation. The abstraction lays bare a regular structure into which many interesting information-flow properties fall. A shared system is represented by a relation. How this model lets one reason about information flow is discussed and the term information flow property is formally defined. Various information-flow properties are described. Composability and probabilistic security properties are addressed     

PUBLIC OPINION,TRADITION, AND INFORMATION HALF-LIFE†

The information needs of a complex society are not met by an information-flow technology invented and developed in traditional societies. This article provides a theoretical framework derived from modern systems theory by which to understand the technology of public opinion policy formation in guidance operations of a complex society. Qualitative models of information flow systems are presented together with a discussion of the kind of society each information flow technology produces. Three are considered: tradition-based information-flow societies, managed information-flow societies (Utopian and elitist), and cybernetic issue-based information-flow societies.     

On serial and parallel information flows,incorporated in a multi-stage production-inventory-system

We consider a chain of production operations separated by inventories, where two different systems-for replenishing the inventories at each stage may be adopted. In the first, the serial information-flow system, each stage works against orders placed only by the following stage. In the second system, called the parallel information-flow system, every stage in the network works against the actual customer demand, materializing at the finished-goods stage.

The basic objective is to show that in the former system the levels of base stock to be maintained at the different stages are more sensitive to changes in the customer demand than in the second system. In fact, in the former case, base-stock fluctuations become larger and larger, progressively back in the chain. Consequently, the production rates also behave in the same way and their variations got multiplied successively back in the chain.     

The past, present, and future of supply-chain automation

We trace 20th-Century developments in the area of supply-chain automation and discuss the history of automation from the viewpoints of material-flow, information-flow, supervision and control, and relationship automation and identify future directions. The main message is that it is important to make balanced investments in all four facets of automation: material-flow, information-flow, supervision and control, and relationship automation to maximize shareholder value. to maximize shareholder value. Just in time to enhance 21st-century industry, material-flow, information-flow, supervision and control, and relationship automation are reaching maturity     

Timing Aware Information Flow Security for a JavaCard-like Bytecode

Common protection mechanisms fail to provide end-to-end security; programs with legitimate access to secret information are not prevented from leaking this to the world. Information-flow aware analyses track the flow of information through the program to prevent such leakages, but often ignore information flows through covert channels even though they pose a serious threat. A typical covert channel is to use the timing of certain events to carry information. We present a timing-aware information-flow type system for a low-level language similar to a non-trivial subset of a sequential Java bytecode. The type system is parameterized over the time model of the instructions of the language and over the algorithm enforcing low-observational equivalence, used in the prevention of implicit and timing flows.     

基于下推系统可达性分析的输出信道信息流检测

提出了一种对含输出信道的命令式语言进行信息流安全性分析的方法。将程序抽象为下推系统,通过自合成将不千涉性转化为安全性属性,将两次相关执行中向输出信道的输出操作分别抽象为由下推规则表示的存储和匹配操作,通过对标错状态的可达性分析验证程序是否满足终止不敏感不干涉性。演化后的方法支持程序的发散执行,通过上界回退算法找到强制终止首次执行所需的最大输出信道上界。实验说明该方法与现有工作相比具有更高的精确性和验证效率。     

Arrows for secure information flow

This paper presents an embedded security sublanguage for enforcing information-flow policies in the standard Haskell programming language. The sublanguage provides useful information-flow control mechanisms including dynamic security lattices, run-time code privileges and declassification all without modifying the base language. This design avoids the redundant work of producing new languages, lowers the threshold for adopting security-typed languages, and also provides great flexibility and modularity for using security-policy frameworks.The embedded security sublanguage is designed using a standard combinator interface called arrows. Computations constructed in the sublanguage have static and explicit control-flow components, making it possible to implement information-flow control using static-analysis techniques at run time, while providing strong security guarantees. This paper presents a formal proof that our embedded sublanguage provides noninterference, a concrete Haskell implementation and an example application demonstrating the proposed techniques.¹     

基于ZigBee 的WSN 定位系统

研究设计了基于ZigBee技术的无线传感器网络定位系统．该方案以TI公司的CC2430／CC2431为核心芯片,结合外围元器件设计网关、参考节点和定位节点模块．详细论述了定位系统的硬件原理和软件设计思想,给出系统原理图和软件设计流程图,以IAREmbeddedWorkbench为平台进行系统软件的开发．采用改进的DV-Distance定位算法,通过仿真比较改进的DV-Distance定位算法与传统算法,验证改进的DV-Distance定位算法可提高定位精度和效率．结果表明该方案是可行的,适合实际应用．     

A general theory of composition for a class of“possibilistic” properties

Since the initial work of Daryl McCullough (1987) on the subject, the security community has struggled with the problem of composing “possibilistic” information-flow properties. Such properties fall outside of the Alpern-Schneider safety/liveness domain, and hence, they are not subject to the Abadi-Lamport Composition Principle. The paper introduces a set of trace constructors called selective interleaving functions and shows that possibilistic information-flow properties are closure properties with respect to different classes of selective interleaving functions. This provides a uniform framework for analyzing these properties, allowing us to construct both a partial ordering for them and a theory of composition for them. We present a number of composition constructs, show the extent to which each preserves closure with respect to different classes of selective interleaving functions, and show that they are sufficient for forming the general hook-up construction. We see that although closure under a class of selective interleaving functions is generally preserved by product and cascading, it is not generally preserved by feedback, internal system composition constructs, or refinement. We examine the reason for this