Abstract: This paper proposes a novel text reversible digital watermarking algorithm. The algorithm preprocesses the original text, using the hamming code to encode the coded values of the original grouped replaceable synonyms, which are regarded as the data bits, and then embeds the obtained parity bits into the text by inserting spaces with matrix coding. It selects a synonym to be replaced to embed the watermarking information according to the codes of the locations of the changed synonyms in a group. During the extraction, in terms of the decoding theory of Hamming code and the rule of encoding the location of the changed synonyms in a group, the watermarking information is extracted and the original text will be restored losslessly. This algorithm not only can recover the original text completely, but also can achieve good invisibility. Therefore, the watermarking proposed scheme has improved practical ability.

Key words: Hamming code, matrix coding, synonym substitution, reversible digital watermarking

摘要： 提出了一种新颖的文本可逆数字水印算法。对载体文本进行预处理，将原始可替换同义词的编码值分组作为信息位进行汉明编码，将获得的监督码元比特流利用矩阵编码的方式通过插入空格嵌入到文本中。水印信息则分组利用同义词修改位置编码的方式选定同义词进行替换来实现嵌入。在提取时利用汉明码的译码原理与可替换同义词分组位置编码规则，提取出水印信息并对原始文本进行无损恢复，即实现了文本可逆数字水印。该算法不仅能有效恢复出原始文本，且具有良好的隐蔽性，增强了水印方案的实际应用能力。

关键词: 汉明码, 矩阵编码, 同义词替换, 可逆数字水印