一种基于双重数字水印和数字签名的文档防篡改算法

提出了一种新的文档防篡改算法，将文档和数字图章的签名信息进行不同处理后，利用小波变换的多分辨率特性，在小波变换的中频部分嵌入鲁棒性水印，而在容易遭受攻击破坏的高频部分嵌入脆弱水印。对文档的各种篡改仿真实验表明，该算法对保证文档的安全性和完整性有很好的效果。

A New Document Algorithm Used to Resist Tamper Based on Dual Digital Watermarking and Digital Signature

In the paper,a new document tamper-resistant algorithm is proposed that combines dig- ital watermarking with digital signature. First, the signature information of document and elec- tronic seal is generated. Secondly, the signature information is encrypted by different key to gener- ate robust watermarking sequence and fragile watermarking sequence. Finally,each of the two se- quences is embedded in various region of wavelet transforming by robust and fragile watermarking algoriti~m. The algorithm utilizes multiresolution characteristics of wavelet transform and over- comes the disadvantage of digital signatures easily removed because of appending the final. It can not only guarantee the integrity of the document itself,but also can detect whether the digital seal has been destroyed. The results of simulation experiments validate the effectiveness of the algo- rithm to ensure the safety and integrity of the document.