An erasable watermarking scheme for exact authentication of Chinese Word documents

At present, most watermarking schemes for authentication of text documents are designed for content authentication, but not for format authentication. This paper proposes a novel erasable text watermarking scheme for exact authentication, which includes the authentication of content and format of Chinese Word documents. In this method, the cover document is divided into two blocks by utilizing the mathematical expression of Chinese characters, and then the hashing values of the text document´s content and format are embedded into the two blocks respectively by setting underlines to Chinese characters and hiding the underlines. In each block, the embedding position is chosen by Chinese character´s strokes and the magic square. The watermark to be authenticated can be extracted without the help of the original watermark and the Word document. When any modification of the watermarked text document´s content and/or format are made, the Chinese text document will fail to pass the authentication. The security analysis and experimental results indicate that the proposed scheme is efficient and secure.