<title>Practical off-line authentication</title>

Abstract

This paper shows our approach for the secure and practical authentication system for the printed data. It is based on the new watermarking technique, which is robust to printer/scanner (ps) distortions and transformation techniques. Ps distortions are random, so it interferes with the self-alignment of the scanned data of a printed image. Therefore, most of conventional watermarking methods are not robust to ps distortions.However, in our system, detection of the watermark is possible by using the correlation between the scanned material of a printed image and the original cover-image. The retrieval of this watermark is fragile to copy and printing distortions more than two times.The documents in which watermarks are embedded can be used as an off-line authentical documents, thus, people had no sooner applied for issuing of a document via internet than they received it in their house or office by using printers. This printed document can be authenticated using our system whether they are genuine or not. We expect our proposed watermarking technology to have wide applications in real life.