Authenticating topological integrity of process plant models through digital watermarking

Process plant models, which feature their intrinsical complex topological relation, are important industrial art works in the field of Computer-Aided Design (CAD). This paper investigates the topology authentication problem for process plant models. Compared with the widely studied watermarking based geometrical information protection and authentication techniques for traditional mechanical CAD drawings, topology authentication is still in its infancy and offers very interesting potentials for improvements. A semi-fragile watermarking based algorithm is proposed to address this interesting issue in this paper. We encode the topological relation among joint plant components into the watermark bits based on the hamming code. A subset of the model’s connection points are selected as mark points for watermark embedding. Then those topology sensitive watermark bits are embedded into selected mark points via bit substitution. Theoretical analysis and experimental results demonstrate that our approach yields a strong ability in detecting and locating malicious topology attacks while achieves robustness against various non-malicious attacks.     

基于标记矢量量化的多重音频数字水印算法

提出一种基于矢量量化和DCT变换的多重音频数字水印算法.该算法将鲁棒水印和脆弱水印分别嵌入到载体音频信号中,同时完成版权保护和音频内容完整性认证的功能.鲁棒水印在进行码字标记的矢量量化过程中嵌入到DCT中频系数中,脆弱水印采用索引约束的方法嵌入到DCT高频系数中.鲁棒水印和脆弱水印都能实现盲提取.实验结果表明,本算法引...     

基于角点检测和奇异值分解的多重数字水印算法

针对多媒体数据的版权保护和完整性认证的多方性,提出一种基于角点检测和奇异值分解的多重数字水印算法．本算法将鲁棒水印嵌入到小波域低频子带角点中,将半脆弱水印嵌入到小波域分块细节子带奇异值中,实验仿真结果表明,水印算法能够抵抗剪切、涂改、滤波、压缩等常见攻击,同时也能够抵抗旋转、缩放等几何攻击,具有较好的鲁棒性和脆弱敏感性,且准确定位篡改区域,可谓一种有效的多重数字水印方案．     

Affine-Transformation-Invariant Public Fragile Watermarking for 3D Model Authentication

We propose a transformation invariant public fragile watermarking scheme for 3D model authentication. The proposed scheme embeds watermarks in a subset a model's faces to keep them in a predefined relationship with neighboring vertices so that any changes will ruin the relationship between the mark faces and neighboring vertices. The proposed scheme has the following advantages: It is invariant to translation, rotation, and uniform scaling operations. These operations do not change the integrity of the original model and should not be regarded as malicious attacks. The proposed method is public— the receiver does not need the original model and watermarks for authentication. It can locate changed regions. Distortion caused by the watermark embedding is controlled by the key settings according to the users' precision requirement. Experimental results show the scheme's effectiveness.     

基于多特征和混沌加密的零水印算法

针对传统数字图像水印版权保护中存在的鲁棒性差和安全性低的问题,为提升不同图像零水印的可区分性,提出了一种基于多特征和混沌加密的零水印算法.首先根据整体与局部的角度提取图像的5维特征:均值特征、方差特征、偏态特征、峰度特征和HOG特征;然后利用新提出的基于混沌映射的块置乱方法加密水印图像;最后基于提取的多特征与置乱后水印,构造零水印信息.在版权认证过程中,首先提取多特征,再结合零水印信息,得到加密后水印;最后对其进行解密;即可实现版权认证.实验结果表明,所提出的方法效率高、安全性高、抗攻击能力强.基于多特征和混沌加密零水印算法综合了数字图像的多方面性质作为特征,稳定性高,提高了算法鲁棒性;同时采用新提出的基于混沌映射的块置乱方法提高了水印图像安全性,有效地解决了图像水印鲁棒性差和安全性低的问题.     

一种MRG骨架树的三维模型检索方法

根据多分辨率Reeb图（MRG）原理,依据测地线函数分割模型,有效地提取反映模型拓扑结构的Reeb图骨架。进而,映射Reeb图为树结构,分析各骨架节点的拓扑属性,并提取其相应区域的离散曲率信息作为局部形状属性。最终,有效结合拓扑和几何形状特征,计算模型的相差度。该方法突出了模型的总体拓扑特征以及模型的表面细节,一系列的实验结果验证了其高效性、鲁棒性。     

网络拓扑特征的不平衡数据分类

现实中的数据集普遍具有非均衡性。针对不平衡分类问题,建立数据集网络结构来充分挖掘隐藏在样本点位置信息外的拓扑特征,分析网络节点的连接特性并赋予节点不同的效率。计算待测节点与每个子网络的相似性测度,依据新型的概率模型,进一步推算出该节点与各子网络的整体性测度。构建了一种基于网络拓扑特征的不平衡数据分类方法,算法中引入不平衡因子c用以减小由正负类样本数量差异所带来的影响。实验结果表明,该算法能有效提高分类精度,特别是对拓扑特征明显的数据集,在分类性能和适应能力上相比传统分类方法都得到进一步提升。     

Tamper detection and self-recovery of biometric images using salient region-based authentication watermarking scheme

Biometric images can be split into regions of salient (ROI) and regions of background (ROB) based on salient region detection. During the process of watermark embedding, salient regions which contain rich-information are less affected by the watermark, therefore can be embedded into more watermarks, and regions of background (ROB) are susceptible to the effect of watermarks, so that they should be embedded lighter or even none in order to preserve the recognition quality of biometric images. In this paper, a novel scheme for tamper detection and self-recovery of biometric images using salient region-based authentication watermarking is proposed. Firstly, we propose a novel multi-level authentication watermarking scheme, which is used to verify the integrity of biometric images. Secondly, biometric data of these biometric images which is used as information watermarks is embedded into themselves. As a result, verification systems can recover the damaged data of original biometric images with hidden information based on tampering detection result. Experimental results and theoretic analysis show that our proposed scheme can detect tampered regions, and recover biometric data while keeping the recognition quality.     

基于变量防篡改的动态图软件水印方案

为了提高动态图软件水印的隐藏容量和鲁棒性,本文提出了一种基于变量防篡改的动态图软件水印方案。该方案利用不同进制形式的数可以相互转化的思想将大的水印信息分割成多个小的水印信息,然后将这些小的水印信息编码成一组图结构,动态地嵌入目标程序中。在编码水印信息时,利用动态图结构中结点的父指针来编码,并使其叶结点与目标程序变量关联,起到防篡改的作用,从而可对水印进行有效的保护。实验结果表明,嵌入水印信息后,目标程序的运行速度和结果都没有明显的变化,但水印对溢出攻击、扭曲攻击和附加攻击等都有明显的抵抗效果,水印也能够准确、方便地被提取出来。该方案的性能明显优于PPCT算法和常量防篡改水印算法。     

基于几何不变性的图像水印

数字水印是信息隐藏技术的一个重要方向,它在版权保护和认证等方面应用的非常广泛。正因为此,水印对攻击具有鲁棒性是很重要的。本文首先介绍水印技术现状及其安全方面的一些研究,然后详细研究图像水印中的几何不变性水印。并着重研究基于不变矩的不变水印以及图像归一化技术。其中,本文所针对的对水印的攻击是几何攻击,包括缩放、翻转和旋转等基本的几何操作。     

基于时频分析的多媒体信息保密技术研究

提出了一个在二维空间时一频分布域的抗几何攻击的多媒体信息保密算法。利用线性频率变化来表示水印信息,通过二维Radon-Wigner变换来检测水印,二维线性调频信号作为水印,这种信号对各种静态滤波器都是不变的,而且还具有几何对称性。在二维Radon-Withe,变换域,作为水印的线性调频信号在遭受缩放、旋转和剪切等线性几何攻击的情况下,仅仅改变其在空间／时-频分布中的位置,由此产生的水印是不可见的,在StirMark测试中效果很好,对于几何攻击是鲁棒的。对比其他的保密算法,该算法尤其对于几何破坏具有更好的鲁棒性,同时还具有优良的频率特性。     

多功能水印在数字图像版权保护中的应用

数字水印是信息隐藏技术的一个重要分支,是一种全新的数字产品保护技术。多功能水印克服了传统数字水印的不足,将多个功能水印嵌入到载体中,具有版权保护、用户跟踪和内容完整性认证三种功能。本文介绍了多功能水印的基本原理,并对典型的多功能水印算法进行了阐述。最后.分析指出了多功能水印技术的研究现状与发展前景。     

小波用于基于遥感影像特征的自适应二维盲水印算法

文章提出了一个有效的基于遥感影像特征的自适应二维盲水印算法。该算法使用灰度图像作为水印,将水印灰度图像进行Arnold置乱加密和小波压缩后,利用相邻特征平均值和奇偶判决法嵌入遥感影像的二阶小波变换域中所选择的子带上,且水印检测不需要原始遥感影像。攻击测试和实验结果表明,该算法具有较好的透明性,强壮性,以及水印检测结果准确,算法复杂度低等优点,对如JPEG有损压缩、中值滤波、附加噪声、伸缩、裁剪、旋转、几何变换、Stirmark攻击等各种影像处理的攻击都具有较强的鲁棒性;且嵌入水印后基本不会影响遥感影像的边缘检测和分类等一些应用。     

一种基于混沌系统的多功能彩色图像数字水印算法

目前,在某一数字产品中仅仅嵌入一种水印已经不能满足人们的要求,在很多情况下,人们需要的是多重水印或多功能水印。本文基于混沌动力系统良好的随机性和初值敏感性,提出了一种空域和DCT域相结合的针对彩色图像的多功能数字水印算法,该算法在彩色图像的蓝色分量中基于混沌随机密钥和LSB技术重复分块嵌入了一幅半脆弱水印,以实现完整性认证及篡改检测,同时分别在红色分量DCT直流系数(DC)中和绿色分量DCT中频系数中各由混沌密钥控制随机嵌入一幅鲁棒水印,这些水印完成版权认证、附加信息检测等。实验结果表明,该算法较好地实现了多功能水印技术。     

Double watermarks of 3D mesh model based on feature segmentation and redundancy information

This paper presents a new robust, blind and good imperceptibility 3D mesh double watermarks algorithm. Two different kinds of watermarks are embedded into one 3D mesh model. One watermarking algorithm based on mesh feature segmentation and the DCT transformation, the other based on redundancy information of 3D model. The two watermarks do not disturb each other during embedding and extracting. Several mesh models are applied to test the robustness, imperceptibility and efficiency of the proposed algorithm. The experimental results show that the proposed watermark scheme can not only keep good imperceptibility but also resist various attacks, such as similarity transformations (translation, rotation, scaling and combinations of the three operations), file attack, signal processing attacks (noising, smoothing and vertex coordinate quantization) and connectivity attacks (cropping).     

基于DWT域的半脆弱“鸡尾酒水印”算法

随着数字图像技术和网络的发展,数字图像的盗版现象日益猖獗,于是数字水印技术应运而生。半脆弱水印技术主要是解决图像内容认证的问题,一般的半脆弱水印都具有鲁棒性不足的缺点。提出一种新的半脆弱“鸡尾酒”水印算法进行图像认证。从水印嵌入的调制策略入手,在图像中隐藏两种正向和负向互补的数字水印,使得水印在受到攻击时至少有一种能够存活,以提高半脆弱水印的鲁棒性。实验证明,这种水印算法具有较好的鲁棒性,能够经受各类攻击。     

A schema for protecting the integrity of databases

Unauthorized changes to databases can result in significant losses for organizations as well as individuals. Watermarking can be used to protect the integrity of databases against unauthorized alterations. Prior work focused on watermarking database tables or relations. Malicious alteration cannot be detected in all cases. In this paper we argue that watermarking database indexes in addition to the database tables would improve the detection of unauthorized alterations. Usually, each database table in commercial applications has more than one index attached to it. Thus, watermarking the database table and all its indexes improve the likelihood of detecting malicious attacks. In general, watermarking different indexes like R-trees, B-trees, Hashes, require different watermarking techniques and exploit different redundancies in the underlying data structure. This diversity in watermarking techniques contributes to the overall integrity of the databases.Traditional relational watermarks introduce some error to the watermarked values and thus cannot be applied to all attributes. This paper proposes a novel watermarking scheme for R-tree data structures that does not change the values of the attributes. Moreover, the watermark does not change the size of the R-tree. The proposed technique takes advantage of the fact that R-trees do not put conditions on the order of entries inside the node. In the proposed scheme, entries inside R-tree nodes are rearranged, relative to a “secret” initial order (a secret key), in a way that corresponds to the value of the watermark.To achieve that, we propose a one-to-one mapping between all possible permutations of entries in the R-tree node and all possible values of the watermark. Without loss of generality, watermarks are assumed to be numeric values. The proposed mapping employs a numbering system that uses variable base with factorial value.The detection rate of the malicious attacks depends on the nature of the attack, distribution of the data, and the size of the R-tree node. Our extensive analysis and experimental results showed that the proposed technique detects data alteration with high probability (that reaches up to 99%) on real datasets using reasonable node sizes and attack model. The watermark insertion and extraction are mainly main memory operations, and thus, have minimal effect on the cost of R-tree operations.     

基于细胞自动机与奇异值分解的零水印算法

针对常规水印算法对JPEG压缩与几何攻击鲁棒性较差的问题,提出了一种基于细胞自动机(CA)变换与奇异值分解(SVD)的零水印算法。首先对图像进行二维细胞自动机变换,分离出低频近似图像并保存作为密钥的变换参数;然后对低频图像分块并在每个子块上进行奇异值分解,通过细胞自动机变换规则在每个子块的奇异值矩阵上构造零水印;最后,图像认证时根据两个图像的水印相似度是否大于阈值来判断图像是否遭遇篡改。通过实验证明,该水印算法具有良好的不可见性和安全性,并且对于JPEG压缩与几何攻击表现出较强的鲁棒性。