用宋词实现高嵌入率文本信息隐藏

High Embedding Ratio Text Steganography by Ci-Poetry of the Song Dynasty

文本信息隐藏是将秘密信息隐藏到文本中的一种技术。与加密后的密文通常是无意义的一串编码不同,文本隐藏生成的隐写文本看起来与普通文本无异,不容易引人怀疑。但是因为文本本身的冗余度低,与图像、视频等载体相比,文本隐藏算法较少且容量偏低。该文提出了一个新的利用宋词的文本隐藏算法,并设计实现了由编码器、解码器、词典和词牌模板组成的系统。秘密信息被隐藏到在字数、行数、句子形式、格律和韵脚等方面符合某个词牌的隐写宋词中。系统在保证良好安全性的同时,嵌入率达到了16%。据我们所知,这是第一个利用特殊体裁的文本信息隐藏算法。

Text steganography is a method of concealing secrets in texts. Different from cryptography which encrypts plain text to meaningless strings, text steganography generates innocuous stego-texts, which arouse less suspicion. However, compared with other types of multimedia documents such as image and video, text is not a well developed kind of carrier in information hiding because of its low redundancy and, consequently, the low embedding ratio achieved. A novel text steganography algorithm using Ci-poetry of the Song Dynasty is proposed in this paper, and the system composed of the encoder, the decoder, the lexicon and the tune template is realized. Secret messages are embedded into stego-Cis of the tune with proper number of lines, words, sentence patterns, rhythm and rhyme. This system reaches 16% embedding ratio while ensuring linguistic robustness. This is, to the best of our knowledge, the first text steganography algorithm making use of special type of literature.