This paper studies the problem of achieving watermark semi-fragility in multimedia authentication through a composite hypothesis testing approach. The embedding of a semi-fragile watermark serves to distinguish legitimate distortions caused by signal processing manipulations from illegitimate ones caused by malicious tampering. This leads us to consider authentication verification as a composite hypothesis testing problem with the watermark as a priori information. Based on the hypothesis testing model, we investigate the best embedding strategy which assists the watermark verifier to make correct decisions. Our results show that the quantization-based watermarking method is more appropriate than the spread spectrum method to achieve the best tradeoff between two error probabilities. This observation is confirmed by a case study of additive Gaussian white noise channel with Gaussian source using two figures of merit: relative entropy of the two hypothesis distributions and the receiver operating characteristic. Finally, we focus on certain common signal processing distortions such as JPEG compression and image filtering, and investigate the best test statistic and optimal decision regions to distinguish legitimate and illegitimate distortions. The results of the paper show that our approach provides insights for authentication watermarking and allows better control of semi-fragility in specific applications.
This paper focuses on the analysis and enhancement of watermarking based security strategies for multimedia authentication. Based on an authentication game between a transmitter and its authorized receiver, and an opponent, security of authentication watermarking is measured by the opponent's inability to launch a successful attack. In this work, we consider two traditional classes of security for authentication: computational security and unconditional security. First we identify authentication watermarking as an error detection problem, which is different from error correction coding in robust watermarking. Then we analyze the computational and unconditional security requirements of an error detection code structure associated with quantization-based authentication watermarking schemes. We propose a novel security enhancement strategy that results in efficient and secure quantization-based embedding and verification algorithms. For computational security, cryptographic message authentication codes are incorporated while unconditional security is obtained by using unconditionally secure authentication codes. Both theoretical analysis and experimental results are presented. They show that using our approach, protection is achieved without significant increase in embedding distortion, and without sacrificing computational efficiency of the embedding and verification algorithms.
In this paper we present an effective steganalyis technique for digital video sequences based on the collusion attack. Steganalysis is the process of detecting with a high probability and low complexity the presence of covert data in multimedia. Existing algorithms for steganalysis target detecting covert information in still images. When applied directly to video sequences these approaches are suboptimal. In this paper, we present a method that overcomes this limitation by using redundant information present in the temporal domain to detect covert messages in the form of Gaussian watermarks. Our gains are achieved by exploiting the collusion attack that has recently been studied in the field of digital video watermarking, and more sophisticated pattern recognition tools. Applications of our scheme include cybersecurity and cyberforensics.
Wireless Multimedia applications increasingly demand low power and bandwidth efficient techniques for content protection. Existing partial encryption methodologies juggle with the difficulties of trading decoding complexity for a higher bit rate, maintaining format compliance yet minimizing the number of components that need to be encrypted, to produce the desired distortion. Source based fingerprinting schemes for content tracking are neither bandwidth efficient nor computationally efficient when coupled with encryption. Thus inspired by the chameleon cipher we present a new algorithm for fingerprinting JPEG compressed images and a simple analytical model based on joint fingerprinting and decryption, as a computationally and bandwidth efficient solution for content protection and tracking.
This paper focuses on the use of nested lattice codes for effective analysis and
design of semi-fragile watermarking schemes for content authentication
applications. We provide a design framework for digital watermarking which is semi-fragile to any form of acceptable distortions, random or deterministic, such that both objectives of robustness and fragility can be effectively controlled and
achieved. Robustness and fragility are characterized as two types of authentication errors. The encoder and decoder structures of semi-fragile schemes are derived and implemented using nested lattice codes to minimize these two types of errors. We then extend the framework to allow the legitimate and illegitimate distortions to be modelled as random noise. In addition, we investigate semi-fragile signature generation methods such that the signature is invariant to watermark embedding and legitimate distortion. A new approach, called MSB signature generation, is proposed which is shown to be more secure than the traditional dual subspace approach. Simulations of semi-fragile systems on real images are provided to demonstrate the effectiveness of nested lattice codes in achieving design objectives.
This work considers the problem of frame collusion in video watermarking, one that is particularly relevant for this media due to the large collection of frames whose temporal inter-relationships may be exploited to facilitate estimation of the mark. Two new components are introduced: A mathematical framework for the statistical analysis of linear collusion and development of potential counterattacks; and a novel video watermarking approach employing the proposed strategies for robustness to collusion as well as other frame-as-image distortions. Experimental results demonstrating the performance of the proposed techniques against two types of collusion attacks are presented.
This paper considers the use of data hiding strategies for improved color image compression. Specifically, color information is piggybacked on the luminance component of the image in order to reduce the overall signal storage requirements. A practical wavelet-based data hiding scheme is proposed in which selected perceptually irrelevant luminance bands are replaced with perceptually salient chrominance components. Simulation results demonstrate the improvement in compression quality of the proposed scheme to SPIHT and JPEG at low bit rates. The novel technique also has the advantage that it can be used to further reduce the storage requirements of algorithms such as SPIHT which is optimized for grayscale image compression.
This paper addresses the issue of robust data hiding in the presence of perceptual coding. Two common classes of data hiding schemes are considered: spread spectrum and quantization-based techniques. We identify analytically the advantages of both approaches under the lossy compression class of attacks. Based on our mathematical model, a novel hybrid data hiding algorithm which exploits the best of both worlds is presented. Theoretical and simulation results demonstrate the superior robustness of the resulting hybrid scheme.
This paper presents a review of some influential work in the area of digital watermarking using communications and information-theoretic analysis. After a brief introduction, some popular approaches are classified into different groups and an overview of various algorithms and analysis is provided. Insights and potential future trends in the area of watermarking theory are discussed.
In this paper, we concentrate on the problem of robust watermarking in the presence of perceptual coding. We first present a watermarking approach called Robust Reference Watermarking (RRW) which can be incorporated into a broad class of watermarking algorithms to improve their performance. Through analysis of this scheme we demonstrate how embedding the watermark using a different perceptual model and domain than for compression can result in improved watermark extraction and detection reliability. Simulation results are also presented to verify our theoretical observations.