对基于量化水印的两频带滤波攻击的估计.pdfVIP

第37 卷 第1 期 电 子 科 技 大 学 学 报 Vol.37 No.1 2008年1月 Journal of University of Electronic Science and Technology of China Jan. 2008 对基于量化水印的两频带滤波攻击的估计 王津申，王执铨 (南京理工大学自动化学院 南京 210094) 【摘要】提出了一种基于量化水印的两频带幅值比例攻击的估计算法。基于量化的水印算法在有加性噪声攻击的情况下 可以达到信道容量，然而对线性时不变滤波攻击没有鲁棒性。该文集中考虑一种使用滤波器组调整信号频谱的多频带幅值比 例攻击，给出受攻击信号的概率密度函数(PDF)模型；使用这个PDF模型的简化近似；给出两频带滤波攻击幅值比例因子的最 大似然估计方法。以合成的音频信号进行实验，结果显示出所提出的估计技术的有效性。 关 键 词 最大似然估计; 多频带; 量化; 水印 中图分类号 TP 309 文献标识码 A Two-Band Amplitude Scale Estimation for QIM Watermarks WANG Jin-shen ，WANG Zhi-quan (School of Automation, Nanjing University of Science Technology Nanjing 210094) Abstract This paper presents a scheme for estimating two-band amplitude scale attack within a quantization-based watermarking context. Although quantization-based watermarking schemes achieve the channel capacity in terms of additive noise attacks, these schemes are not robust against linear time invariant filtering attacks. We concentrate on a multi-band amplitude scaling attack that modifies the spectrum of the signal using an analysis/synthesis filter bank. First we derive the probability density function (PDF) of the attacked data. Second, using a simplified approximation of the PDF model, we derive a maximum likelihood (ML) procedure for estimating two-band amplitude scaling factor. Finally, experiments are performed with synthetic audio signals showing the good performance of the proposed estimation technique under realistic conditions. Key words maximum likelihood estimation; multi-band; quantization; watermarking 基于量化理论的水印算法作为一种信息理论研