Semi-Fragile Watermarking for Copyright Protection and Image Authentication

In this paper, we propose a semi-fragile wattr-marking technology forcopyright protection and image authentication We transform the image into wavelet domain and groupthe four adjacent wavelet coefficients Utilizing the characteristics of the humanvisual system, weembed a digital signal into the average of the four adjacent wavelet coefficients since the mean hasbetter stability than single wavelet coefficient. This method neednt original image when extractsthe watermark. Experimental results show the effectiveness of this method which is robust to commonimage process and fragile to malicious attack.

A Secure Public-key Image Authentication Plan

Digital watermark can be used for image ownership verification orauthentication. In this paper, we propose a new image authentication plan concentrating on itssecurity performance. Digital watermark is first turbo coded, sealed and then processed. In waveletdomain. To enhance security level, public key cryptosystem is utilized to replace traditionalwatermark key. Simulation results are finally given by experiment.

An Image Authentication Method by Grouping Most Significant Bits

In 2011, Chan proposed an image authentication method by producing the parity check bits from pixels whose bits have been rearranged. Due to this rearrangement, the value of the most-significant bit of each tampered pixel can be determined according to its parity check bits. With the help of the most-significant bit of the pixel, the pixel can be recovered by selecting two possible （7, 4） Hamming code words. However, if the distance between two Hamming code words is within a certain range, incorrect selection may occur. Chan＇s method added one additional bit to indicate the correct one. It is trivial that this may degrade the quality of the authenticated image. In this paper, we group four most-significant bits into different groups to form a mapping codebook and the mapping codebook is used to produce authentication data instead of the （7, 4） Hamming code book. The experimental results show that the proposed method has a greater ability to recover tampered areas.

Public key based bidirectional shadow image authentication without pixel expansion in image secret sharing

Image secret sharing(ISS)is gaining popularity due to the importance of digital images and its wide application to cloud-based distributed storage and multiparty secure computing.Shadow image authentication generally includes shadow image detection and identification,and plays an important role in ISS.However,traditional dealer-participatory methods,which suffer from significant pixel expansion or storing auxiliary information,authenticate the shadow image mainly during the decoding phase,also known as unidirectional authentication.The authentication of the shadow image in the distributing(encoding)phase is also important for the participant.In this study,we introduce a public key based bidirectional shadow image authentication method in ISS without pixel expansion for a(k,n)threshold.When the dealer distributes each shadow image to a corresponding participant,the participant can authenticate the received shadow image with his/her private key.In the decoding phase,the dealer can authenticate each received shadow image with a secret key;in addition,the dealer can losslessly decode the secret image with any k or more shadow images.The proposed method is validated using theoretical analyses,illustrations,and comparisons.

Image Authentication Based on Digital Signatureand 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.

Secure and Incidental Distortion Tolerant Digital Signature for Image Authentication

In this paper, a secure and incidental distortion tolerant signature method for image authentication is proposed. The generation of authentication signature is based on Hotelling＇s T-square Statistic （HTS） via Principal Component Analysis （PCA） of block DCT coefficients. HTS values of all blocks construct a unique and stable ＂block-edge image＂, i.e, Structural and Statistical Signature （SSS）. The characteristic of SSS is that it is short, and can tolerate contentpreserving manipulations while keeping sensitive to content-changing attacks, and locate tampering easily. During signature matching, the Fisher criterion is used to obtain optimal threshold for automatically and universally distinguishing incidental manipulations from malicious attacks. Moreover, the security of SSS is achieved by encryption of the DCT coefficients with chaotic sequences before PCA. Experiments show that the novel method is effective for authentication.

Image Splicing Detection Using Generalized Whittaker Function Descriptor

Image forgery is a crucial part of the transmission of misinformation,which may be illegal in some jurisdictions.The powerful image editing software has made it nearly impossible to detect altered images with the naked eye.Images must be protected against attempts to manipulate them.Image authentication methods have gained popularity because of their use in multimedia and multimedia networking applications.Attempts were made to address the consequences of image forgeries by creating algorithms for identifying altered images.Because image tampering detection targets processing techniques such as object removal or addition,identifying altered images remains a major challenge in research.In this study,a novel image texture feature extraction model based on the generalized k-symbolWhittaker function(GKSWF)is proposed for better image forgery detection.The proposed method is divided into two stages.The first stage involves feature extraction using the proposed GKSWF model,followed by classification using the“support vector machine”(SVM)to distinguish between authentic and manipulated images.Each extracted feature from an input image is saved in the features database for use in image splicing detection.The proposed GKSWF as a feature extraction model is intended to extract clues of tampering texture details based on the probability of image pixel.When tested on publicly available image dataset“CASIA”v2.0(ChineseAcademy of Sciences,Institute of Automation),the proposed model had a 98.60%accuracy rate on the YCbCr(luminance(Y),chroma blue(Cb)and chroma red(Cr))color spaces in image block size of 8×8 pixels.The proposed image authentication model shows great accuracy with a relatively modest dimension feature size,supporting the benefit of utilizing the k-symbol Whittaker function in image authentication algorithms.

Recent development of perceptual image hashing

The easy generation, storage, transmission and reproduction of digital images have caused serious abuse and security problems. Assurance of the rightful ownership, integrity, and authenticity is a major concern to the academia as well as the industry. On the other hand, efficient search of the huge amount of images has become a great challenge. Image hashing is a technique suitable for use in image authentication and content based image retrieval （CBIR）. In this article, we review some representative image hashing techniques proposed in the recent years, with emphases on how to meet the conflicting requirements of perceptual robustness and security. Following a brief introduction to some earlier methods, we focus on a typical two-stage structure and some geometric-distortion resilient techniques. We then introduce two image hashing approaches developed in our own research, and reveal security problems in some existing methods due to the absence of secret keys in certain stage of the image feature extraction, or availability of a large quantity of images, keys, or the hash function to the adversary. More research efforts are needed in developing truly robust and secure image hashing techniques.

Chaos-Based Multipurpose Image Watermarking Algorithm

To achieve the goal of image content authentication and copyright protection simultaneously, this paper presents a novel image dual watermarking method based on chaotic map. Firstly, the host image was split into many nonoverlapping small blocks, and the block-wise discrete cosine transform （DCT） is computed. Secondly, the robust watermarks, shuffled by the chaotic sequences, are embedded in the DC coefficients of blocks to achieve the goal of copyright protection. The semi-fragile watermarks, generated by chaotic map, are embedded in the AC coefficients of blocks to obtain the aim of image authentication. Both of them can be extracted without the original image. Simulation results demonstrate the effectiveness of our algorithm in terms of robustness and fragility.

SEMI-FRAGILE WATERMARKING ALGORITHM FOR IMAGE TAMPERS LOCALIZATION AND RECOVERY

Two watermarks are embedded into the original image. One is the authentication watermark generated by secret key, which is embedded into the sub-LSB （Least Significant Bit） of the original image for tamper localization; the other is the recovery watermark for tamper recovering. The original image is divided into 8 x 8 blocks and each block is transformed by Discrete Cosine Transform （DCT）. For each block, some lower frequency DCT coefficients are chosen to be quantized and binary encoded so as to gain the recovery watermark of each block, and the recovery watermark is embedded into the LSB of another block by chaos encryption and authentication chain technology. After the two watermarks being detected, the location of any minute changes in image can be detected, and the tampered image data can be recovered effectively. In the paper, the number of coefficients and their bit lengths are carefully chosen in order to satisfy with the payload of each block and gain the capability of self-recovering. The proposed algorithm can well resist against possible forged attacks. Experimental results show that the watermark generated by the proposed algorithm is sensitive to tiny changes in images, and it has higher accuracy of tamper localization and good capability of the tamper recovery.

Lexicographic Image Hash Based on Space and Frequency Features

A lexicographic image hash method based on space and frequency features was proposed. At first, the image database was constructed, and then color and texture features were extracted from the image blocks including information for every image in the database, which formed feature vectors. The feature vectors were clustered to form dictionary. In hash generation, the image was preproc^ssed and divided into blocks firstly. Then color and texture features vectors were extracted from the blocks. These feature vectors were used to search the dictionary, and the nearest word in dictionary for each block was used to form the space features. At the same time. frequency feature was extracted from each block. The space and frequency features were connected to form the intermediate hash. Lastly, the final hash sequence was obtained by pseudo-randomly permuting the intermediate hash. Experiments show that the method has a very low probability of collision and a good perception of robustness. Compared with other methods, this method has a low collision rate.

IDENTIFICATION OF INPAINTED IMAGES AND NATURAL IMAGES FOR DIGITAL FORENSICS

Image forensics is a form of image analysis for finding out the condition of an image in the complete absence of any digital watermark or signature.It can be used to authenticate digital images and identify their sources.While the technology of exemplar-based inpainting provides an approach to remove objects from an image and play visual tricks.In this paper, as a first attempt, a method based on zero-connectivity feature and fuzzy membership is proposed to discriminate natural images from inpainted images.Firstly, zero-connectivity labeling is applied on block pairs to yield matching degree feature of all blocks in the region of suspicious, then the fuzzy memberships are computed and the tampered regions are identified by a cut set.Experimental results demonstrate the effectiveness of our method in detecting inpainted images.

Image content authentication technique based on Laplacian Pyramid

This paper proposes a technique of image content authentication based on the Laplacian Pyramid to verify the authenticity of image content.First,the image is decomposed into Laplacian Pyramid before the transformation.Next,the smooth and detail properties of the original image are analyzed according to the Laplacian Pyramid,and the properties are classified and encoded to get the corresponding characteristic values.Then,the signature derived from the encrypted characteristic values is embedded in the original image as a watermark.After the reception,the characteristic values of the received image are compared with the watermark drawn out from the image.The algorithm automatically identifies whether the content is tampered by means of morphologic filtration.The information of tampered location is p resented at the same time.Experimental results show that the proposed authentication algorithm can effectively detect the event and location when the original image content is tampered.Moreover,it can tolerate some distortions produced by compression,filtration and noise degradation.

Copy-Move Forgery Verification in Images Using Local Feature Extractors and Optimized Classifiers

Passive image forgery detection methods that identify forgeries without prior knowledge have become a key research focus.In copy-move forgery,the assailant intends to hide a portion of an image by pasting other portions of the same image.The detection of such manipulations in images has great demand in legal evidence,forensic investigation,and many other fields.The paper aims to present copy-move forgery detection algorithms with the help of advanced feature descriptors,such as local ternary pattern,local phase quantization,local Gabor binary pattern histogram sequence,Weber local descriptor,and local monotonic pattern,and classifiers such as optimized support vector machine and optimized NBC.The proposed algorithms can classify an image efficiently as either copy-move forged or authenticated,even if the test image is subjected to attacks such as JPEG compression,scaling,rotation,and brightness variation.CoMoFoD,CASIA,and MICC datasets and a combination of CoMoFoD and CASIA datasets images are used to quantify the performance of the proposed algorithms.The proposed algorithms are more efficient than state-of-the-art algorithms even though the suspected image is post-processed.

Discriminating between photorealistic computer graphics and natural images using fractal geometry

Rendering technology in computer graphics （CG） is now capable of producing highly photorealistic images, giving rise to the problem of how to identify CG images from natural images. Some methods were proposed to solve this problem. In this paper, we give a novel method from a new point of view of image perception. Although the photorealistic CG images are very similar to natural images, they are surrealistic and smoother than natural images, thus leading to the difference in perception. A pert of features are derived from fractal dimension to capture the difference in color perception between CG images and natural images, and several generalized dimensions are used as the rest features to capture difference in coarseness. The effect of these features is verified by experiments. The average accuracy is over 91.2%.

Verifiable image revision from chameleon hashes

In a digital society,the rapid development of computer science and the Internet has greatly facilitated image applications.However,one of the public network also brings risks to both image tampering and privacy exposure.Image authentication is the most important approaches to verify image integrity and authenticity.However,it has been challenging for image authentication to address both issues of tampering detection and privacy protection.One aspect,image authentication requires image contents not be changed to detect tampering.The other,privacy protection needs to remove sensitive information from images,and as a result,the contents should be changed.In this paper,we propose a practical image authentication scheme constructed from chameleon hashes combined with ordinary digital signatures to make tradeoff between tampering detection and privacy protection.Our scheme allows legitimate users to modify contents of authenticated images with a privacy-aware purpose(for example,cover some sensitive areas with mosaics)according to specific rules and verify the authenticity without interaction with the original authenticator.The security of our scheme is guaranteed by the security of the underlying cryptographic primitives.Experiment results show that our scheme is efficient and practical.We believe that our work will facilitate image applications where both authentication and privacy protection are desirable.

Verifiable image revision from chameleon hashes

In a digital society,the rapid development of computer science and the Internet has greatly facilitated image applications.However,one of the public network also brings risks to both image tampering and privacy exposure.Image authentication is the most important approaches to verify image integrity and authenticity.However,it has been cha卜lenging for image authentication to address both issues of tampering detection and privacy protection.One aspect,image authentication requires image contents not be changed to detect tampering.The other,privacy protection needs to remove sensitive information from images,and as a result,the contents should be changed.In this paper,we propose a practical image authentication scheme constructed from chameleon hashes combined with ordinary digital signatures to make tradeoff between tampering detection and privacy protection.Our scheme allows legitimate users to modify contents of authenticated images with a privacy-aware purpose(for example,cover some sensitive areas with mosaics)according to specific rules and verify the authenticity without interaction with the original authenticator.The security of our scheme is guaranteed by the security of the underlying cryptographic primitives.Experiment results show that our scheme is efficient and practical.We believe that our work will facilitate image applications where both authentication and privacy protection are desirable.