基于Hash函数的文本图像脆弱水印算法

Fragile Watermarking Algorithm for the Text Image Based on Hash Function

摘要: 针对文本图像内容真实性和完整性认证的实际需求，提出一种基于Hash函数的文本图像脆弱水印算法。算法思想是首先对文本图像进行分块，然后根据平滑度和连通性来计算每个分块中的可翻转像素点和不可翻转像素点，然后利用Hash函数中的MD5算法加密产生水印信息，最后将这些水印信息嵌入到可翻转像素点中。将在接收到的文本图像中提取的水印信息与之前产生的水印信息相比较，就可以实现文本图像的真实性及完整性认证。该算法有良好的篡改定位能力。

Abstract: Aiming at the actual demand of authenticity and integrity authentication of text image, a fragile watermarking algorithm for text image based on Hash function is proposed. The idea of the algorithm is to first block the text image, and then calculate the reversible and non-reversible pixel points in each block based on smoothness and connectivity. The watermark information is generated by MD5 algorithm in Hash function. Finally, the watermark information is embedded into the reversible pixel points. The watermark information extracted in the received text image is compared with the previously generated watermark information, and the authenticity and inte- grity of the text image can be authenticated. The algorithm has a good ability of tampering posi- tioning.