In this paper we address the usually implicit assumption that digital watermarking has as its main target copyright and copy protection applications. From these target applications a great many conclusions are drawn about the required security of a watermarking system, and in fact, a considerably percentage of the watermarking literature has this very topic as its main focus of attention. In this paper we take a step back, and try to do a more careful analysis of the 'watermarking-is-for-security-applications' paradigm. The intention of this paper is to discuss the meaning of the concept security in the context of watermarking, and try to show that one has to be careful in using analogies from the related field of cryptography.

Considerations on watermarking security

http://poseidon.csd.auth.gr/papers/PUBLISHED/JOURNAL/pdf/Paquet03a.pdf

Wavelet packets-based digital watermarking for image verification and authentication

This paper presents the new digital watermarking algorithm based on the chaotic map. Data can easily be hidden in images by using the least significant bits. In the anticipated algorithm, the logistic map is employed for locating embedding positions of chaotic watermark generation and a novel watermarking scheme is proposed. Simulation results reveal that the proposed technique is feasible and watermarks are indiscernible. The results illustrate that mean of energy, correlation, contrast, and homogeneity analyses of the proposed algorithm are quite optimal.

An efficient scheme for digital watermarking using chaotic map

Installing video cameras in public facilities for surveillance becomes more and more popular. This paper proposes a novel authentication scheme based on chaotic semi-fragile watermarking. The timing information of video frames is modulated into the parameters of a chaotic system. The system output, which is a noise-like signal, is used as a watermark and embedded into the block-based discrete cosine transform domain. The embedded information is demodulated by a maximum likelihood estimator. Temporal tampering can be detected by the mismatch between the extracted and the observed timing information. In addition, the deviation of the extracted watermark from the original one allows us to locate spatial tampering. It is shown that the proposed scheme can satisfy the peculiar requirements of authenticating a digital video surveillance system.

Chaotic Watermarking for Video Authentication in Surveillance Applications

In this paper, theoretical performance analysis of watermarking schemes based on correlation detection is undertaken, leading to a number of important observations on the watermarking system detection performance. Statistical properties of watermark sequences generated by piecewise-linear Markov maps are investigated. Correlation/spectral properties of such sequences are easily controllable, which is a fact that reflects on the watermarking system performance. A family of chaotic maps, namely the skew tent map family, is used to verify the theoretical analysis. Skew tent chaotic sequences are compared against the widely used pseudorandom sequences, indicating the superiority of the former in watermarking applications. The minimum number of samples required for reliable watermark detection is also investigated. Experiments using audio data are conducted to verify the theoretical analysis results.

/pdf/performance-analysis-of-correlation-based-watermarking-4up4032tis.pdf

Performance analysis of correlation-based watermarking schemes employing Markov chaotic sequences

The current paper presents a method for image watermarking based on chaotic sequences produced by different functions. The effect of embedding a chaotic watermark on an image is examined. Extensive experimental results for JPEG and filtering attacks on images watermarked by the different functions are presented together with a comparative study of them. The results show that efficient watermarking methods based on chaos can be designed under certain conditions.

Comparison of different chaotic maps with application to image watermarking

A novel method for image authentication is proposed. A watermark signal is embedded in a grayscale or a color host image. The watermark key controls a set of parameters of a chaotic system used for the watermark generation. The use of chaotic mixing increases the security of the proposed method and provides the additional feature of imperceptible encryption of the image owner logo in the host image. The method succeeds in detecting any alteration made in a watermarked image. The proposed method is robust in high quality lossy image compression. It provides the user not only with a measure for the authenticity of the test image but also with an image map that highlights the unaltered image regions when selective tampering has been made.

L. Pitas

Papers

Comparison of different chaotic maps with application to image watermarking

Image authentication using chaotic mixing systems