实用的完全脆弱认证水印算法*

提出一种完全脆弱认证水印算法用于图像完整性认证、窜改定位和近似恢复被窜改部分。算法基于对原始图像2×2大小分块，计算图像块各像素高6 bit的灰度均值作为水印，利用混沌和置乱技术对水印信息进行加密和确定水印比特嵌入的位置。实验结果表明，该算法简单、安全性高，窜改精确定位到2×2图像块，可对窜改区域近似恢复，具有较好的实用性。

Practical complete fragile authentication watermarking

The paper presented a fragile watermark algorithm for image integrity of the certification, and locate the tampering and image restoration. The algorithm based on the 2×2 pixel image block, then to calculate of high pixel image block the 6 bit gray average as a watermark, the use of chaos and scrambling technology to encrypt watermark information and determine the location of the embedded watermark bit. The results show that: the algorithm is simple, safe, accurate location to tamper with 2 × 2 blocks images can be tampered with the region similar to the recovery, has good practicality.