1. A method implemented in a data processing and printing system for generating a self-authenticating printed document, comprising: (a) obtaining an original document image; (b) processing the original document image to generate processed data; (c) generating a barcode stamp element encoding a code calculated from the processed data generated in step (b); (d) generating a hierarchical barcode stamp by repeating the barcode stamp element in accordance with a pre-defined pattern; (e) printing the hierarchical barcode stamp and the original document image on a front side of a recording medium, wherein the hierarchical barcode stamp is printed with gray tone tiles and the original document image is printed in a black color, the hierarchical barcode stamp and the original document image overlapping each other such that at least some content of the original document image printed in the black color overlaps some gray tone tiles of the hierarchical barcode stamp.