A Model for Embedding and Authorizing Digital Signatures in Printed Documents

It is a desirable feature in a public key infrastructure (PKI) to include the signature information in a printed document for anthenticity and integrity checks, in a way to bind an electronic document to the printed document. However, it is not easy to preserve the digital signature in the printed document because the digital signature is for the text code (or the whole document file), not for the text image (which can be scanned optically) in printed form. So, we propose a practical and secure method for preserving the authorized digital signatures for printed documents. We will derive a printable digital signature scheme from the Korean Certificate-based Digital Signature Algorithm (KCDSA) for secure transaction and utilize the dense two-dimensional barcode, QRcode, for printing out the signature and data in a small area within a printed document.