基于混沌映射、小波变换和RSA加密的数字水印算法

A novel digital watermarking algorithm based on chaos mapping, wavelet transform and RSA cryptography

本文提出了一种新的公开算法的数字水印算法。该算法首先应用Logistic映射构造了一个原始图像的子图,其次把DWT变换作用在这个子图上得到两个子带LH1和HL1,然后对这两个子带进行RSA加密并把水印嵌入在这两个被加密的子带上,接着解密这两个子带并通过IDWT变换重构子图,最后按构成子图的顺序把每一个8×8像素的小块放回到原图中相应位置,从而得到了一个嵌入了水印信息的图像。实验结果表明,通过该算法嵌入的水印具有较好的鲁棒性、安全性和不可感知性。

In this paper,a novel digital watermarking algorithm based on chaos mapping,wavelet transform and RSA cryptography was proposed for static images. Firstly,the sub-image was constructed,which was extracted from the original image by using logistic mapping,two sub-bands andwere obtained by using the effect of DWT transform on this sub-image. Then,these sub-bands were encrypted by using RSA algorithm,the watermark was embedded into the encrypted sub-bands. Then,the two sub-bands were decrypted and the sub- image was＇restructured by using IDWT transformation. Finally,according to the sequence,which had been used to construct above sub-image,every small block （88 pixels） of the watermarked sub-image was put back into the original position of the original image,thus,a watermarked image was obtained. Experimental results showed that the watermark embedded by the proposed algorithm had good robustness, security and imperceptibility.