一种基于非对称水印的图像认证改进算法研究

RESEARCH ON AN IMPROVED IMAGE AUTHENTICATION ALGORITHM BASED ON ASYMMETRIC WATERMARK

提出一种基于非对称水印的图像认证改进算法,算法中将经过BCH编码和混沌序列调制的认证信息作为水印,利用所有者私钥嵌入图像DCT域,嵌入过程根据DCT块的可视噪声阈值(JND)控制,用户可以利用公钥从水印图像中提取认证信息,但无法从公钥中获取任何私钥信息,从而无法破坏或删除水印。实验结果表明:改进算法中水印图像的PSNR值相比原算法增大4.4dB,并且对常见的基于图像处理的攻击,鲁棒性大大提高。

An improved image authentication algorithm based on asymmetric watermark is proposed. The BCH coded authentication data is modulated by chaotic sequence and then embedded into the DCT domain of the image by using the owner＇s private key. The embedding process is controlled by Just Noticeable Difference （JND） of the DCT block. Users can extract the authentication data with the public key ,while they can＇t get the private key to destroy or delete the watermark through the public key. The result of the experiment shows that the embedded image＇s PSNR value of the improved algorithm, is 4.4dB bigger than that of the original algorithm, and the robustness of the improved algorithm against the common image process is increased greatly.