A novel fragile watermarking technique

Block-wise fragile watermarks can be used to reveal maliciously tampered areas in multimedia products. However a forged content containing a cloned fragile watermark can be constructed by using a series of watermarked data. To defeat this type of counterfeit attack, a novel fragile watermarking technique is proposed in which different pseudo-random data are selected for different host products, and the generated fragile watermark is dependent upon the selected information. While inserting the fragile watermark, the pseudo-random information is also robustly embedded into the host data. Because of the difference between the selected information, different watermarked data cannot be used to forge illegal contents containing a valid fragile watermark.

An imperceptible spatial domain color image watermarking scheme

In recent years, tampering and altering of digital images have become easier with the rapid development of computer technologies such as digital image editing tools. Therefore, verification of image integrity and tamper detection of digital images have become a great challenge. Fragile watermarking is the most widely used method for protecting the integrity and content authenticity of the image. In this paper, by using SHA-256 hash function, a novel block based fragile watermark embedding and tamper detection method is proposed. In watermark embedding phase, host image is divided into 32 × 32 non-overlapped blocks. Each 32 × 32 block is then divided into four 16 × 16 nonoverlapped sub-blocks. The entire hash value of the first three sub-blocks is generated as a watermark using SHA-256 hash function. The generated 256-bit binary watermark is embedded into the least significant bits (LSBs) of the fourth sub-block and watermarked image is obtained. In tamper detection phase, the detection of tampered block has been performed by comparing the hash value obtained from the three sub-blocks with the extracted watermark from the fourth sub-block of the watermarked image. The performance of the proposed method has been evaluated by applying linear and nonlinear attacks to the different regions of the watermarked images. Experimental results show that the proposed method detects all the tampered regions of the attacked images and high visual quality of watermarked images has been obtained.

This paper presents an efficient authentication method for JPEG images based on Genetic Algorithms (GA). The current authentication methods for JPEG images require the receivers to know the quantization table beforehand in order to authenticate the images. Moreover, the quantization tables used in the JPEG compression are different for different quality factors, thus increasing the burden on the receivers to maintain several quantization tables. We propose a novel GA-based method which possesses three advantages. First, the computation at the receiver end is simplified. Second, it is no more required for the receivers to maintain quantization tables. Third, the method is resistant against Vector Quantization (VQ) and Copy-Paste (CP) attacks by generating the authentication information which is unique with respect to each block and each image. Furthermore, we develop a two- level detection strategy to reduce the false acceptance ratio of invalid blocks. Experimental results show that the proposed GA-based method can successfully authenticate JPEG images under variant attacks.

Fragile watermarking has the characteristics where the inserted watermark should be easily breakable for a trivial tampering of the image. So, fragile watermarking technique is proposed for the purpose of authentication or tamper detection. In this paper, we propose an efficient image tamper detection method using block-wise technique which is able to detect the tamper locations. In the proposed method, a digital signature is generated from the hash code of the blocks of the final level where the watermark is inserted and the blocks of the upper level where those blocks are included in the image division process and this signature is used as the watermark, which is randomly inserted into selected image blocks. As the result of experiment, the proposed method was confirmed to be able to detect the tampered parts of the image without testing the entire block of the watermarked image.

In the current digital era, patient data in the form of digital medical images in several hospitals are widely used. There are two important thin to use of digital medical images namely the ownership authority (integrity control) and the authenticity of the image (authentication), because digital medical images are very easily manipulated. To maintain the authority of ownership, it needs robust watermarking techniques in which the embedded data is not easily damaged if the image has been manipulated. Meanwhile, to detect the authenticity of the image, it needs fragile watermarking technique in which the embedded data is easily damaged if the image has been manipulated. In this paper, we implement Reed-Solomon code for robust watermark in wavelet domain and SHA-256 for fragile watermark in Hash Block Chaining. The proposed multiple watermarks can be implemented simultaneously on an image so that the integrity control and authenticity of the image detection can be applied at once.

This paper proposes a novel fragile watermarking approach for digital image tamper localization (TL) along with the self-recovery (SR) capability. The host image is first divided into blocks of size 4 × 4 and then, singular value decomposition is performed on each block. The trace of singular matrix is used to compute the TL bits for each block. These 4 × 4 blocks are further divided into blocks of size 2 × 2 to compute the SR information. This SR information is also used for 2nd level of tamper detection in order to enhance the resolution of TL. Proposed scheme implements a self-embedding of TL bits and mapped embedding of SR bits and for that, block mapping is performed. The encrypted combination of both the codes (TL of parent block + SR of mapped block) is inserted in the 1st and 2nd least significant bits of the parent block. Encryption of watermark bits (unique for each watermarked image) helps it to sustain the block based attacks (vector quantization, collage and four scanning attack). Whereas; two level of authentication helps it to sustain content only and constant average attack. The scheme provides an average detection rate of more than 99.5 % and average recovery of 28 dB for a 50 % tampering. The proposed scheme shows a superior performance, when it is compared with the earlier proposed schemes.

This paper covers brief study about some of the latest research trends in self-recovery fragile watermarking algorithms. Fragile watermarking techniques aim to detect modifications to images that are sensitive to any changes, which they are intolerant of even a one-bit alteration. It is desirable to be able to locate the modified areas when a portion of the original content is replaced with other information. Therefore, fragile watermarks are intended for checking the integrity and authenticity of digital contents. Self-recovery means that some significant feature obtained from a selected image itself as a watermark by modifying the pixel values of the original image (host). Once the picture is modified by other users, which has been inserted watermark can be used for tamper detection and recovery images. In this research, we have studied that generally, embedding algorithm for tamper recovery includes three main steps: preprocess the original image and extract important information from it, reorder and embed important information into spatial or frequency domain of host image, and extract the important information from stego-image and use it to recover damaged parts as tamper occurs.

This paper presents a new technique for copyright protection and content authentication of satellite images. The novelty in the presented approach consists in designing a hybrid Discrete Wavelet Transform (DWT), Discrete Cosine Transform (DCT) and hash function based digital image watermarking. In this study, two watermarks are embedded in the cover image called robust copyright watermark and fragile authentication watermark. The robust watermark is embedded in hybrid frequency and wavelet domain by applying DWT and DCT respectively. Such two steps embedding allows the proposed approach to provide better imperceptibility in harmony with the human visual system and offers higher robustness against signal processing attacks. Subsequently, the fragile watermark is embedded in a spatial domain using the hash function approach. The proposed hybrid watermarking technique has been tested on DubaiSat-2 images with 1 meter resolution. The experimental results show that the proposed method is robust against JPEG compression, rotation and resizing attacks. In addition, the multi-watermarked image has a good transparency and the fragile watermark is sensitive to any tampering.

A highly secure oblivious sparse coding-based watermarking system for ownership verification

Several fragile watermarking schemes presented in the literature are either vulnerable to vector quantization (VQ) counterfeiting attacks or sacrifice localization accuracy to improve security. Using a hierarchical structure, we propose a method that thwarts the VQ attack while sustaining the superior localization properties of blockwise independent watermarking methods. In particular, we propose dividing the image into blocks in a multilevel hierarchy and calculating block signatures in this hierarchy. While signatures of small blocks on the lowest level of the hierarchy ensure superior accuracy of tamper localization, higher level block signatures provide increasing resistance to VQ attacks. At the top level, a signature calculated using the whole image completely thwarts the counterfeiting attack. Moreover, "sliding window" searches through the hierarchy enable the verification of untampered regions after an image has been cropped. We provide experimental results to demonstrate the effectiveness of our method.

In the literature, robust reversible watermarking schemes (RWSs) allow the extraction of watermarks after the images have suffered attacks; however, the modified images are compromised. On the other hand, self-recovery schemes will restore the compromised regions of the images, but no secret messages are inserted in these schemes. A framework for robust reversible watermarking with signal restoration capabilities was previously proposed in the literature. This study selects four fragile reversible watermarking techniques and two self-recovery schemes to design different framework configurations. These configurations are evaluated to test the framework’s performance and determine the structure that yields better results in terms of perceptual transparency using a well-known image database as the signal input. It was found that fragile reversible watermarking schemes hold low perceptual distortion, while self-recovery schemes produce high perceptual distortion levels. The inherent characteristics of each algorithm determine, a priori, the behavior of the framework, which is approximated by a proposed equation.

The advancing information technology is playing more and more important role in data mining of relational database.1 The transfer and sharing of databases cause the copyright-related security threats. Database watermarking technology can effectively solve the problem with copyright protection and traceability, which has been attracting researchers' attention. In this paper, we proposed a novel, robust and reversible database watermarking technique, named histogram shifting watermarking based on random forest and genetic algorithm (RF-GAHCSW). It greatly improves the watermark capacity by means of histogram width reduction and eliminates the impact of the prediction error attack. Meanwhile, random forest algorithm is used to select important attributes for watermark embedding, and genetic algorithm is employed to find the optimal secret key for the database grouping and determine the position of watermark embedding to improve the watermark capacity and reduce data distortion. The experimental results show that the robustness of RF-GAHCSW is greatly improved, compared with the original HSW, and the distortion has little effect on the usability of database.

This paper introduces a blind watermarking scheme based on remainder of distance vector between two wavelet blocks. In the proposed scheme, the wavelet coefficients from frequency sub-band LH3 and HL3 have been grouped into two blocks for invisible watermark embedding and extraction. In the next stage, the distance vectors between two blocks are computed and then remainder after division calculated. For embedding 0 and 1 bit, the remainder of distance vectors fixed up to specific values. By increasing divisor, it is possible to embed watermark bits in the host image with more energy; however, this will lead to PSNR reduction. The proposed method, takes advantage of considerable robustness against prevalent attacks and another profit have wide range trade off between watermark embedding energy and the quality of watermarked image with select suitable value of divisor. The experimental results show that the proposed algorithm is robust against image processing attacks and also the comparison analysis indicates that has better performance than the other blind watermarking methods.

The central idea of this paper is to propose an algorithm that embeds the watermark information in host image. The image is divided into a non-overlapping blocks of size 2x2. A matrix is constructed by obtaining mean from every block. With the help of Fibonacci transform, the resultant matrix is scrambled for three times to improve security. Based on the median value a binary watermark is constructed from the scrambled matrix, which is to be embedded within the host image. The operation of embedding and extraction of watermark is done in high frequency domain of Discrete Wavelet Transform. The proposed technique is checked against different noise attacks like salt & pepper and Gaussian, median filtering, image adjustment and histogram equalization. Peak Signal to Noise Ratio (PSNR) and Similarity Ratio (SR) are computed to measure image quality. This watermarking scheme deals with the extraction of the watermark information in the absence of original image, hence the blind scheme was obtained.