Abstract: This article presents ‘signature in signature’, that is the concept of script digital signature, and proposes the direct mode and the mode that needs arbitration about ‘signature in signature’. Considering the characteristic of signature image, the watermark embedding methods about binary and gray images are studied, the possible flippability lookup table of pixels in binary image is found, and the 4-level gray expression way of the signature image is found. Experimental results indicate the proposed LSB watermark embedding method based on 4-level gray has the characteristics of large embedding capacity, good vision invisibility, simplicity and easy realization.

Key words: digital signature, ‘signature in signature’, watermark embedding

摘要： 介绍“签名的签名”，即笔迹数字签名的概念，提出直接和需仲裁的“签名的签名”之2种结构模式。针对签名图像的特点，对二值图像水印嵌入方法和灰度图像水印嵌入方法进行研究，建立二值图像的像素可翻转值查找表，给出签名图像的4级灰度表示法。实验结果表明，基于4级灰度的LSB水印嵌入方法具有嵌入容量大、不可见性好、简单易行等特点。

关键词: 数字签名, “签名的签名”, 水印嵌入

CLC Number: 

• TP391.41