Abstract: Aiming at the bug of current block based fragile watermarking scheme，a novel fragile watermarking scheme based on chaotic hash function is proposed in this paper.Firstly chaotic hash function is implemented on each image block to generate binary image，then XOR the binary image with the chaotic binary image generated by chaotic system to attain binary fragile watermark，after being scrambled，the binary fragile watermark is embedded into LSB plane of original image；difference image is used to realize authentication.Theoretical analysis and experimental results show the proposed scheme has good invisibility，and ability of resisting VQ attack，differentiating the tamper type，even the super security.

摘要： 针对现有分块脆弱水印的缺陷，提出了一种基于混沌Hash函数的脆弱水印算法。该方案通过将原始图像分块后做混沌Hash，生成原始图像的摘要，与由混沌映射生成的混沌二值图像异或后生成二值脆弱水印，置乱加密后嵌入原始图像的LSB平面；认证时通过差值图像定位篡改的区域。理论分析和实验仿真表明提出的水印算法不可见性好，能够有效抵抗VQ攻击，并能够区分篡改的类型，安全性高。