Systems and methods for converting physical signatures to electronic signatures are described that utilize public keys encoded in ink strands embedded or suspended in a printing material that is used to create the physical signature. A user signs a paper document with the signed ink and the paper document...http://www.google.com.tw/patents/US20030065923?utm_source=gb-gplus-share專利 US20030065923 - Systems and methods for converting physical signatures to electronic signatures
