一种基于可逆数字水印的图像认证方案

AN IMAGE AUTHENTICATION SCHEME BASED ON REVERSIBLE WATERMARKING

针对医疗图像、遥感图像等敏感数字图像在认证水印的嵌入过程中不能引入失真的特点,提出一种基于可逆数字水印的图像完整性认证方案:首先提取图像特征,将其作为hash函数的输入;再用图像发送者的私钥对hash值进行数字签名;最后将数字签名作为水印数据,利用图像相邻像素点差值直方图的特征,轻微改变图像像素点的灰度值来可逆嵌入水印数据。方案实现简单,水印嵌入后图像失真小,认证通过后还可以完全恢复原始图像。理论和实验证明水印嵌入后,PSNR值能达到51.14dB以上。

Aiming at the characteristic that some sensitive digital images（such as medical images and remote sensing images,etc.） can not bring in distortion in the process of authenticating watermark embedding,this paper proposes a new image integrity authentication scheme based on reversible digital watermarking.First,the image features are extracted and used as the input of hash function,then the hash value is signed in digital form using the private key of image sender to form crypto signature,finally,the digital signature is employed as the watermark data,and the feature of difference histogram of image＇s adjacent pixel points is utilised to slightly alter the grey degree value of the image pixel points to reversibly embed watermark data.The proposed scheme is quite simple and the execution time is short.Moreover,the distortion of image is quite small when the watermark is embedded and the original image can be completely restored after the authentication.It is proved theoretically and experimentally that the lower bound of PSNR（peak-signal-to-noise-ratio） of watermarked images can achieve 51.14dB after the watermark has been embedded.