Patent ID: 7089213

Claim:
A method of operating a secure check printing system for printing an unalterable negotiable instrument, the method comprising: receiving payment information to include on the negotiable instrument, the payment information including a payee name and an amount; encrypting a representation of the payment information to generate an encrypted value utilizing an asymmetric algorithm and a first key; and generating a print file for delivering to printer for printing, onto blank check stock, the payment information, a representation of the encrypted value, and a second key to create a face of the negotiable instrument, the second key being different than the first key but mathematically related to the first key such that deciphering the encrypted value utilizing the asymmetric algorithm and the second key yields the representation of the payment information; wherein the step of generating a print file for delivery to a printer comprises: converting the encrypted value to a numeric character sequence comprising exclusively numerals and including the numeric character sequence in the file such that the printer prints, onto blank check stock, the payment information, the numeric character sequence, and the second key on face of the negotiable instrument; and including the numeric character sequence and the second key in MICR font positioned such that it is printed upside down across the top of the negotiable instrument.