A method of producing a 2D barcode on an article including a laser markable layer, wherein the 2D barcode includes a primary information pattern representing primary information, which can be read by a 2D-barcode-reader, and a secondary information pattern embedded within the 2D barcode, which is difficult to reproduce without alteration, includes a laser marking step of exposing the laser markable layer with an infrared laser thereby forming the secondary information pattern of the 2D barcode.