Reversible watermarking for 2D CAD engineering graphics based on improved histogram shifting

According to the characteristics of the coordinates and phases in 2D CAD engineering graphics, difference histograms are constructed. Consequently, two reversible watermarking schemes based on difference histogram shifting are put forward. The first scheme HS_C implements the integer part of coordinate values to construct the adjacent difference histogram and hides messages in the peak and zero point pairs. The scheme can achieve high capacity and good invisibility in the graphics with high correlated coordinates. Instead of coordinates, the second scheme HS_P adopts the integer part of the phase value as the cover data, and the watermark is embedded by shifting and modifying the difference histogram of the phase. It is robust against translation, rotation and even scaling. Experimental results show that both schemes are strictly reversible. The proposed schemes have great potential to be applied for content authentication or secret communication of 2D CAD engineering graphics.     

A reversible watermarking scheme for two-dimensional CAD engineering graphics based on improved difference expansion

Difference expansion is widely used in reversible watermarking for raster images, but it cannot be applied to data with low correlation, due to its large distortion. In this paper, an improvement is made to difference expansion technology to make it suitable for two-dimensional (2D) computer-aided design (CAD) engineering graphics. Based on improved difference expansion (IDE), a reversible watermarking scheme for 2D CAD engineering graphics is proposed. First, all vertices of the 2D CAD engineering graphics are extracted, and then the relative coordinates of these vertices are calculated. Finally, the encrypted watermark is embedded into the scale factor of the relative coordinates by using IDE technology. Experimental results show that the proposed scheme has a large capacity, good imperceptibility, and is robust against operations such as transformation, rotation, and equal scaling.     

A reversible watermarking for authenticating 2D CAD engineering graphics based on iterative embedding and virtual coordinates

Multimedia Tools and Applications - Aim to authenticate the integrity of 2D CAD engineering graphics, a reversible watermarking method based on iterative embedding and virtual coordinates is...     

二维工程图中基于分数傅里叶变换的盲水印算法

提出了一种基于二维工程图的水印算法。该方法提取二维工程图中线段的相对坐标向量,构造一维复数信号。通过分数傅里叶变换得到复数信号的变换系数,根据水印的大小和分数傅里叶变换系数的之间的关系,对变换系数的幅值进行调整来嵌入水印。该方法是盲水印算法,在提取水印时不需要原始工程图。实验表明,该算法对平移、旋转、缩放等攻击具有良好的鲁棒性,同时具有良好的安全性。     

块截断编码的图像自嵌入半脆弱水印算法

目的 数字图像自嵌入水印技术是解决图像篡改检测和恢复问题的主要技术手段之一,现有的自嵌入水印技术存在着认证粒度不高、嵌入水印后的图像失真较大,且无法抵抗滤波等操作。为提高图像自嵌入水印的认证粒度以及抵抗滤波等处理操作的能力,提出了一种基于块截断编码的图像自嵌入半脆弱水印算法。方法 水印生成与嵌入：首先,将图像进行块级别的二级划分,分别生成粒度为4×4和2×2的图像块;然后,利用块截断编码对每个4×4图像块进行压缩编码,生成2×2图像块的恢复水印,并对恢复水印进行哈希生成2×2图像块的认证水印;最后,将恢复水印和认证水印级联构成自嵌入水印,嵌入到映射块中。篡改认证与恢复：首先,将某个4×4图像块提取的水印与该块生成的水印比较,判别该图像块的2×2子块是否通过认证;最后,依据认证结果对2×2图像块实施恢复。结果 该算法产生的水印图像的峰值信噪比（peak signal-to-noise ratio,PSNR）均高于44 dB,在50%的篡改率下,恢复后的图像质量可达到32.7 dB。该算法生成水印并在图像上嵌入大约需要3.15 s,恢复图像大约需要3.6 s。结论 算法利用块截断编码,有效缩短了生成的水印长度,保证嵌入水印后图像的质量。此外,通过引入的可容忍修改阈值,使得水印能够对滤波等图像处理操作具有一定的鲁棒性,同时保证对图像的恶意篡改具有敏感性。最后通过与最近典型方法的对比实验,验证了算法在嵌入水印后图像质量、恢复图像质量等方面的优势。     

A numerically stable fragile watermarking scheme for authenticating 3D models

This paper analyzes the numerically instable problem in the current 3D fragile watermarking schemes. Some existing fragile watermarking schemes apply the floating-point arithmetic to embed the watermarks. However, these schemes fail to work properly due to the numerically instable problem, which is common in the floating-point arithmetic. This paper proposes a numerically stable fragile watermarking scheme. The scheme views the mantissa part of the floating-point number as an unsigned integer and operates on it by the bit XOR operator. Since there is no numerical problem in the bit operation, this scheme is numerically stable. The scheme can control the watermark strength through changing the embedding parameters. This paper further discusses selecting appropriate embedding parameters to achieve good performance in terms of the perceptual invisibility and the ability to detect unauthorized attacks on the 3D models. The experimental results show that the proposed public scheme could detect attacks such as adding noise, adding/deleting faces, inserting/removing vertices, etc. The comparisons with the existing fragile schemes show that this scheme is easier to implement and use.     

A semi-fragile watermarking scheme for authenticating audio signal based on dual-tree complex wavelet transform and discrete cosine transform

In this paper, a novel semi-fragile watermarking scheme for authenticating an audio signal based on dual-tree complex wavelet transform (DT-CWT) and discrete cosine transform (DCT) is proposed. Specifically, the watermark data are efficiently inserted into the coefficients of the low-frequency sub-band of DT-CWT taking advantages of both DCT and quantization index modulation (QIM). First, the original digital audio signal is segmented and then performed with DT-CWT. Second, based on the energy compression property, the low-frequency sub-band coefficients of the DT-CWT domain are performed with DCT, and the DC component is utilized to embed one distorted watermark bit by the QIM technique. Finally, inverse DCT and DT-CWT are orderly implemented on the watermarked coefficients of each audio segment to get a watermarked audio signal. Simulation results show that the hybrid embedding domain constructed by DT-CWT and DCT is effective, and the proposed watermarking scheme is not only inaudible, but also robust against content persistent non-malicious audio signal processing operations, such as MP3 compression, noise addition, re-sampling, re-quantization, etc. Furthermore, the proposed scheme can effectively authenticate the veracity and integrity of audio content and greatly expands the applicability of the audio watermarking scheme.     

Image authentication based on digital signature and semi-fragile watermarking

This paper proposes an authentication scheme for JPEG images based on digital signature and semi-fragile watermarking. It can detect and locate malicious manipulations made to the image, and verify the ownership of the image at the same time. The algorithm uses the invariance of the order relationship between two DCT coefficients before and after JPEG compression to embed image content dependent watermark, therefore the watermark can survive the JPEG lossy compression. Since the scheme is based on the security of the cryptographic hash function and public key algorithm, it is believed to be secure to the extent that cryptography is believed to be. Theoretical analysis and experimental results show that the proposed scheme has the desired property and good performance for image authentication.     

2维CAD工程图小波域可逆水印

针对2维CAD工程图对高精度的要求,提出一种采用改进量化索引调制（IQIM）的2维CAD工程图小波域可逆水印算法。该算法首先提取2维CAD工程图中所有实体的顶点信息,并对顶点信息依次进行顶点变换和离散小波变换以获取仿射变换不变性,然后使用改进的量化索引调制算法将加密后的水印信息嵌入到所有的细节系数中。实验结果表明,该算法具有良好的可逆性、不可见性和较大的水印容量,且对图形平移、旋转、均匀缩放等攻击具备较好的鲁棒性。     

基于分数傅里叶变换的二维工程图水印算法

提出一种基于离散分数傅里叶变换（DFRFT）的二维工程图数字水印算法。该算法分块提取工程图中线段的相对坐标线构造复值信号量,将水印嵌入复值信号量的分数傅里叶变换频谱（FRT）中。实验表明,该算法对平移、旋转、缩放、部分实体删除或添加等攻击具有良好的鲁棒性,同时具有良好的安全性。     

基于B-spline矢量图形数字水印方法

提出了一种针对矢量图形的数字水印算法,用于矢量图形的版权保护。算法利用了B-spline良好的持续逼近曲线形状的特点,将水印嵌入到B-spline的控制点坐标中。经实验证明,该算法对于通常的图形几何变换,如平移、旋转、缩放以及局部修改攻击,均有令人满意的鲁棒性。     

基于一维正态云模型的半脆弱文本水印

根据云模型和人眼视觉系统的特点,给出了一种利用一维正态云模型和文本字体颜色变化的半脆弱性水印方案.通过正向云发生器生成云滴,所有云滴组合产生水印信息,修改文字的颜色值嵌入水印.在提取水印信息时,通过提取字体颜色特征,重构云图来验证.实验结果表明,本算法是一种半脆弱的文本水印.     

基于MPEG-I /II视频内容认证的半脆弱水印方案

提出了一种基于MPEG-I/II视频内容认证的半脆弱水印方案，该水印方案对视频内容恶意篡改敏感，对类似于视频重编码等内容保持操作鲁棒。水印方案完全建立在视频压缩域之上，利用视频图像块与块之间不变的能量关系构建基于内容的特征码，加上版权信息、控制信息生成完整的水印认证码，运用边信息通信方式嵌入视频VLC域。通过对提取出的水印信息和重构的认证码进行比较，实现了对视频的内容认证。该文最后给出了实验结果，证明了该方案的可行性。     

一种面向图像内容认证的半脆弱数字水印算法*

提出了一种面向内容认证的半脆弱数字水印算法。该算法利用混沌系统的类随机性和遍历性的特点,将载体图像分成两部分,其中一部分用于提取基于图像特征的水印,另外一部分则用来嵌入提取的特征水印,水印信号嵌入到矩阵奇异值(SVD)较大的数据中。实验表明算法达到了不可见性、盲检测性等半脆弱水印的基本要求,并保证在对常见的JPEG压缩稳健的同时,能有效地区分偶然失真和恶意窜改。     

A multipurpose audio watermarking algorithm with synchronization and encryption

We propose a new multipurpose audio watermarking scheme in which two complementary watermarks are used.For audio copyright protection,the watermark data with copyright information or signature are first encrypted by Arnold transformation.Then the watermark data are inserted in the low frequency largest significant discrete cosine transform(DCT) coefficients to obtain robustness performance.For audio authentication,a chaotic signal is inserted in the high frequency insignificant DCT coefficients to detect tampered regions.Furthermore,the synchronization code is embedded in the audio statistical characteristics to resist desynchronization attacks.Experimental results show that our proposed method can not only obtain satisfactory detection and tampered location,but also achieve imperceptibility and robustness to common signal processing attacks,such as cropping,shifting,and time scale modification(TSM).Comparison results show that our method outperforms some existing methods.     

基于离散余弦变换的数字水印算法

针对数字产品的版权保护问题,提出了一种基于离散余弦变换的数字水印算法;通过对水印攻击原理的分析,提出了由认证中心分密钥和作者分密钥组成的水印密钥生成方案,较好地解决了水印在抵抗解释攻击方面问题,提高了水印信息的安全性.实验结果表明,该算法不仅具有良好的不可见性,而且对JPEG压缩、高斯噪声和图像剪切等攻击有理想的鲁棒性.     

一种基于特征的二维工程图信息隐藏算法

针对数字工程图的版权保护问题,基于二维工程图的特征提出了一种信息隐藏算法。该算法先获得工程图中的有序线段集并进行乱序处理,然后将待嵌入的信息转化为伪随机序列,并以此为依据并结合人体视觉系统特征对乱序线段集中线段的线型按序进行修改,从而实现信息的隐藏。试验结果表明,该信息隐藏算法对旋转、平移以及均匀缩放等攻击具有较好的鲁棒性。     

一种新的方程式软件水印算法*

针对方程式重排序算法易于受到随机重排序技术攻击的问题,提出了基于中国剩余定理的软件水印算法,并通过引入水印认证中心达到水印的认证.该算法运用中国剩余定理将水印进行分解,将分解得到的序列与方程式系数序列做相关运算,使得水印与方程式的系数相关联.对得到的序列与所选取的除数序列及倍数作进一步处理生成密钥,该密钥仅属版权所有者且处于保密状态.验证版权时,版权所有者对密钥解密并进行相关运算,提取出正确的水印.该算法的水印提取完全实现了盲检测,且无须向程序中添加任何代码.实验结果表明,该算法鲁棒性较良好,程序代码的长度及运行速度也不受影响,其性能优于方程式重排序等算法.     

基于图像小波矩特征调制的鲁棒水印

为了提高水印抵抗旋转、剪切等攻击的能力，提出了一种新的基于小波矩特征调制的鲁棒性水印算法。小波矩具有旋转、平移、缩放不变性，且具有小波的多分辨率特性，可以利用水印信息调制载体的低阶小波矩实现信息的隐藏，并且对各阶矩的隐藏能力进行比较。实验表明该算法对剪切、旋转等几何攻击具有很强的抵抗能力，且水印检测不需要原载体的参与。     

基于混沌的DWT域多功能图像数字水印算法

提出了一种基于混沌的DWT域多功能图像数字水印算法。原始水印分为鲁棒水印和半脆弱水印,分别用于版权保护和图像认证。根据不同的应用,鲁棒水印又分为容量小但鲁棒性要求相对高和容量大但鲁棒性要求相对低的两种,它们和半脆弱水印分别嵌入DWT域的不同部分。并利用广义猫映射置乱鲁棒水印和Logistic混沌系统生成半脆弱水印以提高安全性。实验表明,嵌入水印后的图像视觉质量好,其中鲁棒水印能抵抗各种常规图像处理,半脆弱水印能准确地检测并定位内容篡改。