Patent ID: 7784681

Claim:
A method of tracking a security document, the security document having disposed thereon or therein coded data including a plurality of coded data portions, each coded data portion being indicative of an identity of the security document and further indicative of at least part of a signature, the signature being a digital signature of at least part of the document, wherein the coded data comprises one of rotation indicating or orientation indicating data, the method including, in a computer system: receiving, from a sensing device operable to sense the coded data, indicating data indicative of the identity of the security identity and at least part of predetermined padding, the padding being at least one of a predetermined number and a random number; updating, using the received indicating data, a tracking data entry specific to the security document stored in a data store, the tracking data entry being indicative of: (i) the identity of the security document, and (ii) tracking information indicative of a plurality of transactions performed using the security document, and the locations of the plurality of transactions; determining, from the indicating data, a determined identity and at least one determined signature part; and authenticating the security document using the determined identity and the at least one determined signature part.