E-Stamping: A Mechanism to Authenticate Printed Documents

Abstract

The research is focused on the printed document authentication mechanism called Electronic stamping (E-stamping) which is in turn based on the frequency domain watermarking tech- niques designed for images. Discrete fourier transformation (DFT) is used in the E-stamping mechanism, since its robustness to the print-scan process. The proposed mechanism can be used for di erent kind of applications like electronic stamp, secured identity card, passport, driver license, certi cate identi cation, electronic ticketing, etc. Especially, it can be used in wide variety of E-government applications. The main purpose of E-stamping is to digitally embed a seal which contains identi cation information on the document to prevent its illegal reproduction. E-stamping consists of two major processes, namely, digital signature embedding and signature extraction. In the embed- ding process, the digitally-signed data relevant to the application can be embedded not only to gray scale images but also to color images imperceptibly prior to it being printed. At the data veri cation process, the printed image that contains the embedded signature is converted into digital form using a scanner. The signature is extracted from the scanned image and it is compared with the signature generated using the content of the document to check the validity. A 64 bit digitally-signed binary data can be inserted to an image with size of 256 256 pixels with high accuracy and low visual distortion.