The existing digital data verification methods are able to detect regions that have been tampered with, but are too fragile to resist incidental manipulations. This paper proposes a new digital signature scheme which makes use of an image's contents (in the wavelet transform domain) to construct a structural digital signature (SDS) for image authentication. The characteristic of the SDS is that it can tolerate content-preserving modifications while detecting content-changing modifications. Many incidental manipulations, which were detected as malicious modifications in the previous digital signature verification or fragile watermarking schemes, can be bypassed in the proposed scheme. Performance analysis is conducted and experimental results show that the new scheme is indeed superb for image authentication. keywords: Digital signature, Wavelet transform, Authentication, Fragility, Robustness. The preliminary version of this paper will be published in [14] (http://smart.iis.sinica.ed...

Image authentication verifies the originality of an image by detecting malicious manipulations. This goal is different from that of image watermarking which embeds into the image a signature surviving most manipulations. Existing methods for image authentication treat all types of manipulation equally (i.e., as unacceptable). However, some applications demand techniques that can distinguish acceptable manipulations (e.g., compression) from malicious ones. In this paper, we describe an effective technique for image authentication which can prevent malicious manipulations but allow JPEG lossy compression. The authentication signature is based on the invariance of the relationship between DCT coefficients of the same position in separate blocks of an image. This relationship will be preserved when these coefficients are quantized in a JPEG compression process. Our proposed method can distinguish malicious manipulations from JPEG lossy compression regardless of how high the compression ratio is. We also show that, in different practical cases, the design of authenticator depends on the number of recompression times and on whether the image is decoded into integral values in the pixel domain during the recompression process. Theoretical and experimental results indicate that this technique is effective for image authentication.

The objective of this paper is to propose an image authentication scheme, which is able to detect malicious tampering of images even they have also been incidentally distorted. By modeling incidental and malicious distortions as Gaussian distributions with small and large variances, respectively, we propose to embed a watermark in the wavelet domain by a mean quantization technique. Due to the various probabilities of tamper response at each scale, these responses are integrated to make a decision on the tampered areas. Statistical analysis is conducted and experimental results are given to demonstrate that our watermarking scheme is able to detect malicious attacks while tolerating incidental distortions. 1. INTRODUCTION Image authentication becomes very important due to the availability of Internet. To save bandwidth and storage, digital images are usually transmitted or stored in a compressed form. In addition, images may be processed by blurring or equalization operations by user...

Three novel blind watermarking techniques are proposed to embed watermarks into digital images for different purposes. The watermarks are designed to be decoded or detected without the original images. The first one, called single watermark embedding (SWE), is used to embed a watermark bit sequence into digital images using two secret keys. The second technique, called multiple watermark embedding (MWE), extends SWE to embed multiple watermarks simultaneously in the same watermark space while minimizing the watermark (distortion) energy. The third technique, called iterative watermark embedding (IWE), embeds watermarks into JPEG-compressed images. The iterative approach of IWE can prevent the potential removal of a watermark in the JPEG recompression process. Experimental results show that embedded watermarks using the proposed techniques can give good image quality and are robust in varying degree to JPEG compression, low-pass filtering, noise contamination, and print-and-scan.

In a variety of applications, there is a need to authenticate a source that may have been degraded, transformed, edited, or otherwise modified, either intentionally or unintentionally. We develop a formulation of this problem, and identify and interpret the associated informationtheoretic performance limits. The results are illustrated through application to binary sources with Hamming distortion measures, and to Gaussian sources with quadratic distortion measures.

With the ambient use of digital images and the increasing concern on their integrity and originality, consumers are facing an emergent need of authenticating degraded images despite lossy compression and packet loss. In this paper, we propose a scheme to meet this need by incorporating watermarking solution into traditional cryptographic signature scheme to make the digital signatures robust to these image degradations. Due to the unpredictable degradations, the pre-processing and block shuffling techniques are applied onto the image at the signing end to stabilize the feature extracted at the verification end. The proposed approach is compatible with traditional cryptographic signature scheme except that the original image needs to be watermarked in order to guarantee the robustness of its derived digital signature. We demonstrate the effectiveness of this proposed scheme through practical experimental results.

Abstract—We have seen an explosion of data exchange in the Internet and the extensive use of digital media. Consequently, digital data owners can quickly and massively transfer multimedia documents across the Internet. This leads to wide interest in multimedia security and multimedia copyright protection. We propose a novel hybrid digital video watermarking scheme based on the scene change analysis and error correction code. Our video watermarking algorithm is robust against the attacks of frame dropping, averaging and statistical analysis, which were not solved effectively in the past. We start with a complete survey of current watermarking technologies, and noticed that none of the existing schemes is capable of resisting all attacks. Accordingly, we propose the idea of embedding different parts of a single watermark into different scenes of a video. We then analyze the strengths of different watermarking schemes, and apply a hybrid approach to form a super watermarking scheme that can resist most of the attacks. To increase the robustness of the scheme, the watermark is refined by an error correcting code, while the correcting code is embedded as a watermark in the audio channel. It optimizes the quality of the watermarked video. The effectiveness of this scheme is verified through a series of experiments, in which a number of standard image processing attacks are conducted, and the robustness of our approach is demonstrated using the criteria of the latest StirMark test. Index Terms—Digital watermarking, discrete wavelet transform (DWT), hybrid, scene change, video. I.

A new algorithm for embedding several watermarks into the same original source is proposed in this paper. Instead of conventional watermark embedding algorithms that embed one watermark in one specific domain, we propose algorithms for embedding multiple watermarks into different compression domains to protect the ownership of the original images. The proposed schemes for embedding and extraction in different domains vary from the existing methods reported in the literature. Simulation results show their robustness for surviving intentional attacks and, hence, their effectiveness in protecting copyrights. They are also easy to implement.

The existing digital image editing tools have made the authentication of digital images an important issue. The objective of this paper is to propose an image authentication scheme, which is able to detect malicious tampering while tolerating some incidental distortions. By modeling the magnitude changes caused by incidental distortion and malicious tampering as Gaussian distributions with small and large variances, respectively, we propose to embed a watermark by using a mean quantization technique in the wavelet domain. The proposed scheme is superior to the conventional quantization-based approaches in terms of the credibility of authentication. Statistical analysis is conducted to show that the probabilities of watermark errors caused by malicious tampering and incidental distortion will be, respectively, maximized and minimized when our new scheme is applied. Experimental results demonstrate that the credibility of our method is superior to that of the conventional quan...

Abstract. Due to the explosion of data exchange on the Internet and the extensive use of digital media, it has been of intense interest to digital data owners in multimedia security and multimedia copyright protection. In this paper, a comprehensive approach for protecting and managing video copyrights with watermarking techniques is introduced. We propose a novel digital video watermarking scheme based on the scene change analysis and genetic algorithm. Robustness and fidelity are the essential requirements of a successful watermarking scheme. In pervious work, a robustness scene-based watermarking scheme is proposed. We focus on improving the fidelity of the scheme in this paper. The fidelity of the scheme is enhanced by applying a genetic algorithm, which optimizes the quality of the watermarked video. The effectiveness of this scheme is verified through a series of experiments. 1