Abstract: Stego is a steganography software using text to hide secret information. It transforms any binary file into nonsense text based on a dictionary either given explicitly or built on the fly from a source document. By studying the mechanism of Stego, this paper proposes two steganalysis methods to detect it. When the first letters of words in dictionary are lowercases, the steganalysis method based on the signature characters is used to detect Stego; When it’s not in above condition, the steganalysis method based on statistical characters is used to detect Stego. The results of experiments show that the two methods have high credibility.

Key words: Steganalysis, Stego, Text, Information hideing

摘要： Stego是一种基于文本的信息隐藏工具，它利用字典将秘密信息转化为无语法但结构与自然语言相似的文本以达到隐秘通信的目的。通过研究Stego的机理，文章提出了文本隐写软件Stego的隐写分析方法。当隐藏所使用的字典单词全以小写字母开头时，可以通过基于标志特征的隐写分析方法检测出隐秘文本；当上述条件不满足时则通过基于统计特征的隐写分析方法检测出隐秘文本。实验表明两种方法均有很高的可靠性。

关键词: 隐写分析, Stego, 文本, 信息隐藏