Patent ID: 7441712

Claim:
A method for authenticating a security document for a security transaction, the security document having disposed thereon or therein coded data including a plurality of coded data portions each encoding an identity of the security document and a respective part of a digital signature of at least part of the identity retained by a computer system, the method including, in a sensing device: sensing at least one coded data portion; generating, using the sensed coded data portion, indicating data at least partially indicative of: the identity of the security document; and the signature part encoded by the sensed coded data portion; and, transferring the indicating data to a computer system, the computer system being responsive to the indicating data to: determine, from the indicating data, a received identity, and a received signature part; authenticate the security document by verifying that the received signature part is part of the digital signature of the received identity and thereby allowing use of the security document in the security transaction.