Information hiding by stochastic diffusion and its application to printed document authentication

The use of image based information exchange has grown rapidly over the years in terms of both e-to-e image storage and transmission and in terms of maintaining paper documents in electronic form. Further, with the dramatic improvements in the quality of COTS (Commercial-OfF-The-Shelf) printing and scanning devices, the ability to counterfeit electronic and printed documents has become a widespread problem. Consequently, there has been an increasing demand to develop digital watermarking, information hiding and covert encryption methods which can be applied to both electronic and printed images (and documents) for the purposes of authentication, prevent unauthorized copying and, in the case of printed documents, withstand abuse and degradation before and during scanning. In this paper we consider the background to a new method to hiding image based information by diffusing it with a stochastic field (uniformly distributed noise). This 'diffusion only' approach is used specifically to design a system for authenticating printed information that is robust to a low resolution 'print-scan cycle'.