Patent ID: 7965862

Claim:
A method for authenticating and tracing an industrially printed material, comprising: applying a mark in a manner that is invisible for the naked eye based on the creation of pseudo-random defects on the surface of said material by the means of an industrial printing technology using a liquid substance capable of solidification upon drying in which the liquid substance is deposited over at least a portion of the material with a regular thickness in areas other than individual locations corresponding to active dots of the mark and having a modulated thickness in areas corresponding to the active dots of the mark, the active dots representing a pseudo-random two dimensional pattern initialized by a key, said substance modifying at least one optical characteristic of said material, said defects having an individual size ranging from 10 to 500 micrometers; and detecting said mark at a later time by measuring the signal to noise ratio of the two dimensional digital signal obtained by cross-correlating said pattern with a digital two-dimensional digital image of the printed material.