Towards Linguistic Steganography: A Systematic Investigation of Approaches, Systems, and Issues
Richard Bergmair · 2004
“ad astra per aspera.” Steganographic systems provide a secure medium to covertly transmit information in the presence of an arbitrator. In linguistic steganogra-phy, in particular, machine-readable data is to be encoded to innocuous natural language text, thereby providing security against any arbitra-tor 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 natu-ral language processing. A detailed description is given of the systems built so far. The ideas and approaches they are based on are sys-tematically presented. Objectives for the functionality of natural lan-guage stegosystems are proposed and design considerations for their construction and evaluation are given. Based on these principles cur-rent systems are compared and evaluated. A coding scheme that provides for some degree of security and ro-bustness 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.