基于嵌入色彩的自适应色彩优化

针对基于控制点参数位置的自动色彩优化方法无法有效表达全局数据特征的问题,提出一种基于嵌入色彩的自适应色彩优化方法,该方法包含色彩嵌入位置估计和嵌入色彩优化2个核心过程.首先基于色彩可辨别性以及数据分布选取合理的色彩嵌入位置,然后在固定色彩嵌入位置的基础上,建立能量优化方程求解最优嵌入色彩,使其既满足视觉可辨别,又能够尽量保证与原始色彩表的一致性.在此基础上,开发了一个交互式数据可视探索系统,该系统可有效支持整体数值感知和局部感兴趣区域探索.为了评估方法的有效性和系统实用性,在6种不同特性的色彩表、8种具有不同数据分布的数据集上开展用户实验以及案例分析.实验表明,该方法相比其他方法可产生细节更加丰富的视觉信息,为用户探索数据提供条件.     

基于离散时间排队的ARQ性能分析

基于自动请求重传(ARQ)协议的工作原理,提出基于离散时间带有启动机制的Geom/G/1排队模型。使用嵌入马尔可夫链方法推导出排队系统的稳态队长、等待时间、忙期和忙循环等性能指标的解析表达式,给出ARQ协议中数据帧的平均响应时间、信道利用率、系统吞吐量等性能指标的解析表达式。利用仿真工具Matlab进行计算机仿真,数值例子证明了性能指标解析表达式的正确性。     

基于差分扩展的高效数字图像嵌入算法研究

针对某些特殊情况需要将数据进行安全可靠传输的问题,本文提出一种基于差分扩展的将数据嵌入数字图像的算法。即将数字图像作为待传输数据的载体,按照差分扩展原理将待传数据嵌入到数字图像后进行发送,再由接收方按照与之相逆的方法进行数据恢复。经过实验表明,该算法与其它算法比较,在保证图像有很低的失真率的同时还确保更高的数据嵌入率     

基于多分类器融合的未知嵌入率图像隐写分析方法

提出一种基于多分类器融合的未知嵌入率图像隐写分析方法.通过建立多个不同嵌入率下的训练分类器模型,得到对测试图像的多个局部决策值;然后将得到的局部决策值转化为证据,并根据各分类器的漏检率和虚警率,对各局部决策值分配权重;最后由基于权重系数的D-S(Dempster-Shafer)证据理论推理得到最终的决策.针对LSB匹配隐写的实验结果表明,本文方法改善了未知嵌入率下的隐写检测性能.     

针对EzStego隐写图像的检测方法

针对基于调色板图像的EzStego隐写算法，在分析比较了目前常见的χ^2统计分析与RS分析方法后，指出了这两种方法在低嵌入率的EzStego隐写图像检测中的不足及其产生问题的主要原因，考虑到EzStego隐写算法的以下两个显著特征：颜色对及顺序嵌入，提出了一种基于颜色对频度统计分析的新型检测算法。实验结果表明，这种方法适用于EzStego隐写图像的检测，在低嵌入率情况下，其检测率和虚警率优于χ^2统计分析与RS分析方法。该方法在使虚警率降低1～2倍的情况下，检测率达到87％，而其他两个方法的检测率只有63％～69％，该新方法19～24个百分点。     

一种按用户角色管理菜单操作权限的方法

基于数据库应用系统的安全考虑,应该从多个层面控制用户的权限。通过控制是否能对某些菜单进行操作,提出了一种按角色来控制用户权限的方法,并通过一个用PowerBuilder开发的数据库应用系统为例,分析介绍了这种方法的原理和特点、数据库表的设计、程序实现等内容。     

基于整数小波阈值嵌入的无损数据隐藏

提出了基于整数小波阈值嵌入的无损数据隐藏方法。在图像的小波子带系数的最低位（LSB）嵌入隐藏数据，将数据嵌入到小波CDF(2,2)的高频子带系数中，符合人的视觉系统原理(HVS)。并使用直方图调整的方法防止溢出。小波阈值嵌入利用阈值T控制小波系数在最低位是否插入隐藏数据。该方法嵌入数据容量大(相同PSNR)，PNSR高(相同容量）。通过对CorelDraw图像库1096幅图像测试，证明了提出的方法是有效的。     

基于高7位平面嵌入的灰度图像可逆数据隐藏算法

现有基于直方图平移的可逆数据隐藏算法都致力于提高嵌入率,而忽略了算法所产生边界图的大小;数量较大的边界图将不能够有效存储进而影响算法的实施。本文对现有典型算法存在的这一问题进行分析,并给出了解决方法。最后本文提出了基于高7位平面嵌入的灰度图像可逆数据隐藏算法,与传统可逆数据隐藏算法使用全部位平面进行数据嵌入不同,本文所提出的算法使用高7位平面当做数据载体。由高7位平面构成的载体图像具有像素值分布更加集中的特点,因而使用该载体图像进行可逆数据嵌入能够有效的控制边界图大小并且明显的提高嵌入率。实验结果表明,本文所提出的算法在提高嵌入率的同时,还能使嵌入附加数据的图像具有高的峰值信噪比值。     

基于小波域扩谱的无损数据隐藏

该文提出一种基于小波域扩谱的无损数据隐藏方法。该方法根据扩谱原理把数据嵌入到图象整数小波变换后的高频子带系数中;通过嵌入伪信息的方式,解决了在提取信息时无法判断在哪些系数上嵌入了水印信息的问题;另外,为防止小波反变换时图象灰度溢出问题,使用了直方图调整技术。实验结果表明,该方法能嵌入大容量的数据信息,同时保持很好的视觉效果,在图象认证及伪装通讯等领域具有广泛用途。     

基于TCP／IP的嵌入式网络电子称量技术研究

基于TCP／IP的嵌入式网络电子称量技术改变了传统电子衡器的操作控制方式，实现了电子衡器的远程控制。本文在分析了基于TCP／IP的嵌入式网络电子称量技术系统结构的基础上，讨论了在电子衡器中嵌入TCP／IP协议栈及Web服务器的具体实现，并阐述了电子衡器的远程控制原理。     

基于MME和IRB的信息隐写算法

为提高隐写算法的安全性,提出一种基于MME(modified matrix encoding)和IRB(iterative random blocking)的信息隐写算法。通过分析基于IRB的隐写算法流程,找到了其载密图像质量下降的主要原因,使用MME改进了该算法。实验结果表明,相比于IRB隐写算法,改进算法提高了载密图像质量,同时提高了抵抗盲检测的能力。改进算法表明了使用隐写编码可提高嵌入效率,从而提高隐写算法的安全性。     

Hiding data: a high-capacity distortionless approach

The widespread use of 3D models has become an interest in steganography. In this paper, we present a novel data hiding method for 3D models. Based on the representation information, the key idea is to consider the vertex index as a message block. A message consists of three types of message blocks, namely, unique, repeated and 1-bit or 0-bit repetitions blocks. Three embedding methods, namely, vertex index embedding (VIE), dynamic-length bit-string mapping (DBM), and repeated bits embedding (RBE), each best for a respective type of message block are devised. All message vertices are then arranged in the light of proposed vertex order and output as the stego-model. The message block is extracted from the vertex of the stego-model by the order of vertex sequence and its index in the ordered vertex list. While integrating the proposed methods our scheme gains high capacity compared to existing techniques while preserving reasonable robustness. In addition, our method is efficient, 25 times faster than previous techniques. With high capacity, several novel applications like content annotation for large documents, 3D meta model for related resources, etc., becomes possible, making the 3D model as an excellent data container.     

Efficient large payloads ternary matrix embedding

Matrix embedding (ME) can be exploited to improve the embedding efficiency for steganography by making fewer changes to the cover data. In ME, the sender and recipient agree on a parity check matrix (PCM) in advance. The PCM will be used by the sender to embed secret message into the cover data and later by the decoder to extract the embedded message. The embedding performance of ME is greatly influenced by the PCM thus the choice of PCM is crucial for ME. On the other hand, since larger sized PCM usually leads to higher embedding efficiency, how to keep the balance between the computational complexity and the embedding efficiency is also an important problem of ME. Based on these considerations, an efficient ternary ME method for large payloads data embedding is proposed in this paper. We utilize a specific matrix construction for PCM to improve embedding efficiency and a sub-optimal search strategy to reduce the computational complexity. The experimental results show that the proposed method achieves good embedding efficiency at low time cost and it outperforms some state-of-the-art works. For example, for a cover image with 512 × 512 pixels at an embedding rate of 1 bit per pixel, the proposed method can be implemented within 0.5 second in a personal computer with a rather high embedding efficiency as 3.89.     

A steganography embedding method based on edge identification and XOR coding

In this paper, we present a novel image steganography algorithm that combines the strengths of edge detection and XOR coding, to conceal a secret message either in the spatial domain or an Integer Wavelet Transform (IWT) based transform domain of the cover image. Edge detection enables the identification of sharp edges in the cover image that when embedding in would cause less degradation to the image quality compared to embedding in a pre-specified set of pixels that do not differentiate between sharp and smooth areas. This is motivated by the fact that the human visual system (HVS) is less sensitive to changes in sharp contrast areas compared to uniform areas of the image. The edge detection method presented here is capable of estimating the exact edge intensities for both the cover and stego images (before and after embedding the message), which is essential when extracting the message. The XOR coding, on the other hand, is a simple, yet effective, process that helps in reducing differences between the cover and stego images. In order to embed three secret message bits, the algorithm requires four bits of the cover image, but due to the coding mechanism, no more than two of the four bits will be changed when producing the stego image. The proposed method utilizes the sharpest regions of the image first and then gradually moves to the less sharp regions. Experimental results demonstrate that the proposed method has achieved better imperceptibility results than other popular steganography methods. Furthermore, when applying a textural feature steganalytic algorithm to differentiate between cover and stego images produced using various embedding rates, the proposed method maintained a good level of security compared to other steganography methods.     

基于词向量和卷积神经网络的垃圾短信识别方法

对垃圾短信进行过滤识别研究具有重要的社会价值和时代背景意义。针对传统的人工设计短信特征选择方法中存在数据稀疏、特征信息共现不足和特征提取困难的问题,提出一种基于词向量和卷积神经网络（CNN）的垃圾短信识别方法。首先,使用word2vec的skip-gram模型根据维基中文语料库训练出短信数据集中每个词的词向量,并将每条短信中各个词组所对应的词向量组成表示短信的二维特征矩阵;然后,把特征矩阵作为卷积神经网络的输入,通过卷积层的不同尺度卷积核提取多尺度短信特征,以及利用1-max pooling池化策略得到局部最优特征;最后,将局部最优特征组成融合特征向量放入softmax分类器中得出分类结果。在10万条短信数据上进行的实验结果表明,在特征提取方式相同的情况下,基于卷积神经网络模型的识别准确率能够达到99.5%,比传统的机器学习模型提高了2.4%~5.1%,且各模型的识别准确率均保持在94%以上。     

A New Steganographic Method for Data Hiding in Microsoft Word Documents by a Change Tracking Technique

A new steganographic method for data hiding in Microsoft Word documents by a change tracking technique is proposed. The data embedding is disguised such that the stegodocument appears to be the product of a collaborative writing effort. Text segments in the document are degenerated, mimicking to be the work of an author with inferior writing skills, with the secret message embedded in the choices of degenerations. The degenerations are then revised with the changes being tracked, making it appear as if a cautious author is correcting the mistakes. The change tracking information contained in the stegodocument allows the original cover, the degenerated document, and, hence, the secret message to be recovered. The extra change tracking information added during message embedding is vital in a normal collaboration scenario, and so hinders ignorant removals by skeptics. Experiments demonstrate the feasibility of the proposed method     

Adaptive Data Hiding,Using Pixel-Value-Differencing and LSB Substitution

With the development of Internet communications, the security of message sending on the Internet has become very important. This article proposes a new adaptive data hiding method with a large data-embedding capacity for gray-scale images to raise the security of sending a message between sender and receiver in networks. At first, the image is divided into some blocks consisting of two consecutive pixels. If the values of both pixels are small, fewer secret bits will be embedded within the two pixels, otherwise, the difference value of two pixels is calculated, and according to the obtained difference value, the method will estimate the number of embedding bits into LSBs of two pixels. This number is adaptive and depends on the range to which the difference value belongs. A readjusting phase is presented to keep the difference of value pixels in the same range before and after embedding. Experimental results show that our method has increased the capacity of embedding bits in comparison with the several other methods.     

图像隐写分析中小波系数相关性的研究与应用*

提出了一种针对空域图像隐写的盲检测方法。利用互信息分析秘密信息嵌入对图像小波系数在尺度方向和空间方向相关性的影响,使用马尔可夫模型挖掘小波系数层内和层间相关性,提取转移概率矩阵作为特征。针对LSB匹配和随机调制隐写算法的实验表明,此方法能有效检测未经JPEG压缩过的含密图像,相比现有空域盲检测方法,对低嵌入率含密图像的正确检测率提高约8%14% 。     

二值文本图像信息隐藏分析

通过大量实验发现,基于块中心跳转的二值文本图像密写算法,其二值文本干净图像和密写图像的游程统计特性差别较大,而二值文本密写图像和二次密写图像的游程统计特性差别较小。基于该规律提出一种二值文本图像信息隐藏分析方法,对待测图像进行二次密写,计算待测图像和密写图像游程统计函数的差异值,当差异值大于门限时,待测图像是干净图像,否则是密写图像。通过分类实验的方法确定了几种典型字体的判决门限。实验结果表明,利用该方法和相关判决门限,密写检测率可达99．9％。     

Using quad smoothness to efficiently control capacity-distortion of reversible data hiding

One of the main uses of data hiding is to protect secret messages being transmitted on the Internet. Reversible data hiding can fully recover the original host image after extracting the secret message. It is especially suitable for applications where, after extracting the secret message, the quality of the recovered host image cannot be compromised, such as for medical or military image data.Many difference-expansion-based (DE-based) reversible data hiding methods have made use of a threshold value to control the stego-image's quality. Usually repeated trial and error is required to find a relatively good threshold with acceptable capacity-distortion behavior. This paper introduces a scheme that does not require a threshold value, such as is used in Alattar's quad-based reversible data hiding. It applies a prediction of quad of quads smoothness to determine the embedding sequence. The proposed scheme is shown to perform better than other DE-based schemes. Results showed that it has the ability of maintaining embedding quality at all capacity levels, especially when the embedding capacity is at low to medium levels.