基于字符编码和图像分块的文档完整性检测方法

提出了一种安全的、不可见的、通用的易碎文档数字水印方法.嵌入到文档图像中的水印完全依赖于文档内容及字符间距等格式,可有效检验文档的完整性和可信性.根据文档中字符的Unicode编码值及各个字符在文档中对应的位置,构造一个矩阵D,计算D经过一系列变换后的特征值,可以生成水印序列.若文档被篡改,则根据该文档提取出的水印也将发生改变.同时,通过将文档图像分块,可预测可能发生篡改的位置.

A Method for the Detection of Document Integrity Based on Character Encoding and Image Blocking

It proposes a secured,invisible and general method of fragile document watermarking.The watermark embedded into the original document image depends on the content and the format such as the space between two characters of the document absolutely,which is effective for detecting the integrity and credibility of the documents.According to the Unicode value and position of each character in the document,it constructs a matrix D and calculates the eigen of D after a serious of transformation,which generates a sequence about the watermark.If the document has been tampered,the watermark extracted could also be different from the original one.This method can predict the possible location of being tampered by the way of document image blocking.