Abstract: Watermark technique is one of effective means of copyright protection.On the basis of a detailed analysis of natural language watermarking,a text watermarking algorithm based on sentence length is proposed.The watermarking,with the modification of sentence length by sentence transformations,can be embedded into the document.The sequence of paragraphs and sentences is permuted using DES and hashing table in order to improve the watermarking robustness before watermarking embedding,and during the embedding,redundant embedding and majority voting are introduced.Analysis and provement show that the watermarked documents have good robustness and the false positives is extremely small.

摘要： 数字水印技术是文本版权保护的有效手段之一。通过对自然语言文本水印特征的分析,提出了一种基于句长的中文文本水印算法。该算法通过句式变换修改句子的长度来嵌入水印,在水印嵌入前采用DES加密算法并结合散列表技术对段和句子的索引序列进行置乱处理以提高水印的鲁棒性,水印嵌入时算法引入了冗余嵌入和大多数投票机制,通过分析表明该算法具有较高的鲁棒性和较低的误判率。