A Method of Linguistic Steganography Based on Collocationally-Verified Synonymy

Abstract

A method is proposed of the automatic concealment of digital information in rather long orthographically and semantically correct texts. The method does not change the meaning of the source text; it only replaces some words by their synonyms. Groups of absolute synonyms are used in a context independent manner, while the groups of relative synonyms are previously tested for semantic compatibility with the collocations containing the word to be replaced. A specific replacement is determined by the hidden information. The collocations are syntactically connected and semantically compatible pairs of content words; they are massively gathered beforehand, with a wide diversity in their stability and idiomacity. Thus the necessary linguistic resources are a specific synonymy dictionary and a very large database of collocations. The steganographic algorithm is informally outlined. An example of hiding binary information in a Russian text fragment is manually traced, with a rough evaluation of the steganographic bandwidth. © Springer-Verlag 2004.