作　　者： ; ; (李大捷）;

机构地区： 中山大学信息科学与技术学院

出　　处： 《自动化学报》 2009年第7期841-850,共10页

摘　　要： 近年来,数字水印安全性的研究日益受到重视.对数字水印安全性的攻击是指对水印通信中密钥的估计,水印的安全性可以用对水印密钥估计的Cramer-Rao界(Cramer-Raobound,CRB)来衡量.扩频水印的安全性具有重要的研究价值.以往的研究假设图像载体呈高斯分布,忽视了实际自然图像载体分布的非高斯性对水印安全性的影响.本文利用高斯尺度混合(Gaussian scale mixture,GSM)模型描述自然图像载体的非高斯特性,从理论上分析了扩频水印在KMA(Known messageattack)和WOA(Watermarked only attack)攻击下的CRB和MCRB界(Modified Cramer-Raobound),得出了扩频水印安全性与观测次数、秘密载波长度、水印嵌入能量以及嵌入信息分布特征的关系.本文的工作对于设计新一代的安全、鲁棒水印具有重要的意义. Watermarking security has emerged as the domain of extensive research in recent years. Attack to the security of watermarking is to estimate the secret keys used in watermarking communications. The security level of watermarking system can be evaluated by Cramer-Rao bound （CRB） for secret keys estimation. As a widely used method, the security issue of add spread spectrum （Add-SS） based watermarking has drawn great attention. The previous works on watermarking security were mainly based on the assumption that host signal was Gaussian distributed and ignored the impacts of non-Gaussian characteristics of nature images. With incorporation of the Gaussian scale mixture （GSM） model for host signals, this paper presents a theoretical analysis on the security of Add-SS watermarking system. By giving the CRB and MCRB （modified Cramer-Rao bound） for the estimation of secret carriers under KMA （known message attack） and WOA （watermarked only attack）, this paper also reveals the factors that may influent the Add-SS watermarking security such as the times of observation, the length of secret carriers, the embedding energy, and the distribution of embedded messages. The results obtained in this paper will be helpful for designing the new secure and robust watermarking system.

关 键 词： 模型 扩频水印 安全性 界

领　　域： [自动化与计算机技术] [自动化与计算机技术]