Excerpts from the Abstract:

Steganographic systems provide a secure medium to covertly transmit information in the presence of an arbitrator. In linguistic steganography, in particular, machine-readable data is to be encoded to innocuous natural language text, thereby providing security against any arbitrator tolerating natural language as a communication medium.

So far, there has been no systematic literature available on this topic, a gap the present report attempts to fill. This report presents necessary background information from steganography and from natural language processing. A detailed description is given of the systems built so far. The ideas and approaches they are based on are systematically presented. Objectives for the functionality of natural language stegosystems are proposed and design considerations for their construction and evaluation are given. Based on these principles current systems are compared and evaluated.

A coding scheme that provides for some degree of security and robustness is described and approaches towards generating steganograms that are more adequate, from a linguistic point of view, than any of the systems built so far, are outlined.