Patent ID: 7353398

Claim:
A method of verifying authenticity of a document comprising the steps of: calculating trial security information by combining critical information from the document and a description of a serially numbered authenticator item which is not part of the document but is associated with the document, the document being capable of cancellation by defacing or destroying the unique authenticator item; comparing the trial security information with a issuer security information read from the document; determining that the document is an only negotiable copy of the document when the trial security information agrees with the issuer security information read from the document and the separate authenticator is present with the document; and determining that the document is an authentic not negotiable copy of the negotiable document when the calculated security information agrees with the security information read from the security information field and the separate authenticator is not present with the document; and determining that the document is not an authentic copy of the negotiable document when the calculated security information does not agree with the security information read from the security information field and is not negotiable; canceling the document in all of its copies by defacing or destroying the unique authenticator item.