A method for determining whether a candidate barcode is genuine involves acquiring an image of an original barcode, wherein the original barcode includes a plurality of modules; determining, from the image of the original barcode, a deviation of a position of at least one of the plurality of modules of the original barcode from an idealized grid; encoding the deviation as signature data for the original barcode; storing the signature data for the original barcode on a storage device; acquiring an image of the candidate barcode, wherein the candidate barcode includes a plurality of modules; determining, from the image of the candidate barcode, a deviation of a position of at least one of the plurality of modules of the candidate barcode from the idealized grid; retrieving the signature data for the original barcode from the storage device; comparing the signature data for the original barcode with signature data for the candidate barcode; and making a determination that the candidate barcode is genuine or not genuine based on a result of the comparison.