一种半脆弱数字水印算法

摘要

随着移动设备的广泛使用,利用微信、QQ、邮箱等APP平台传播多媒体数据越来越便捷.为了保护多媒体数据的完整性,并对多媒体数据的完整性进行认证,数字水印技术应运而生.针对完整性认证和篡改定位,提出了一种半脆弱数字水印算法.通过将原始图像进行整数小波变换,以避免浮点数的舍入误差;将图像进行二级整数小波变换,利用矩阵范数量化方法,将水印嵌入到整数小波域的中、高频细节子带中;采用Logistic混沌序列对水印信息进行加密,以达到提高水印安全性的目的.再利用整数小波逆变换,得到含水印图像.通过涂改、剪切、压缩、加噪等常用攻击方法,实验结果表明,算法兼具鲁棒性、脆弱敏感性,能够准确定位篡改区域,是一种有效的半脆弱数字水印方案.%With the widespread use of mobile devices,WeChat,QQ,mail and other APP platform to spread multimedia data is more convenient.In order to protect and authenticate the integrity of the multimedia data,the digital watermarking technology is emerged.Aiming at its integrity authentication and tamper location,a semi-fragile digital watermarking algorithm is proposed.Integer wavelet transform is made for the original image to avoid rounding error of floating-point numbers,and that of second level is conducted for image to embed watermarks to intermediate and high frequency progeny details of integer wavelet domain with matrix norm quantization.In order to guarantee the security of watermark,the watermark information is encrypted by the Logistic chaotic sequence.Then the inverse integrated wavelet transform is applied to obtain the watermarking image.By altering,sheafing,compression,noise adding and other common attack methods,the experiments show the algorithm has both robustness and sensitivity,and also exactly locates distorted parts,which is an effective semi-fragile digital watermarking method.