Multimedia content screening using a dual watermarking and fingerprinting system

An improved attack analysis on a public-key spread spectrum watermarking

“…To this end, we consider minimum probability of error estimate, minimum mean square estimate and linear minimum mean square estimate of the watermark signal, and the attacks based on these estimates. As it turns out, minimum mean square error estimate attacks perform better than the ones proposed in [1]. These results are applicable to more general data hiding scenarios.…”

“…All signals in the setup, namely the host data, the watermark sequence, and all detector keys are generated Fig. 1 The spread spectrum fingerprinting setup presented in [1] independently from each other.The notation utilized in this manuscript is very similar to that of [1]. In the rest of the paper, bold fonts denote real vectors of length-N unless stated otherwise.…”

“…This setup is vulnerable to collusion attack in the sense that when an attacker breaks the decoder, he is able to get the original watermark sequence w. Given the marked data y, he can extract the now-available watermark sequence from that vector to obtain the unmarked and original host data x. In order to discourage the attackers and trace the guilty parties, the following modification is proposed in [1]. Each decoder is revealed the watermark sequence plus another sequence, c i which has a mean zero and variance B.…”

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We analyze the fingerprinting method in Kirovski et al (2002) and suggest attacks that are better than the ones presented therein. To do this, we observe and use some extra information available in the system.

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“…Section 3 is the core of the paper and there we present the new attacks that are powerful than the one discussed in [1]. We analyze the system performance under the class of estimation attacks presented in the same section.…”