Strengthening Spread Spectrum Watermarking Security via Key Controlled Wavelet Filter
Spread spectrum watermarking security can be evaluated via mutual information. In this paper, we present a new method to reduce mutual information by embedding watermark in the key controlled wavelet domain. Theoretical analysis shows that the watermark signals are diffused and its energy is weakened when they are evaluated from the attacker’s observation domain, and it can lead to higher document-to-watermark energy ratio and better watermark security without losing robustness. Practical algorithms of security tests using optimal estimators are also applied and the performance of the estimators in the observation domain is studied. Besides, we also present a novel method of calculating the key controlled wavelet filter, and give both numerical and analytical implementations. Experiment results show that this method provides more valid parameters than existing methods.
KeywordsWatermarking security Spread spectrum Key controlled wavelet Parameterizations Mutual information
This work was supported by the NSF of China under 61170281, NSF of Beijing under 4112063, Strategic and Pilot Project of CAS under XDA06030601, and the Project of IIE, CAS, under Y1Z0041101 and Y1Z0051101.
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