The invention relates to a security marking printed via intaglio process, corresponding engraved intaglio printing plate, and methods and devices for producing, encoding/decoding and authenticating said security marking. The security marking comprising multitone 2D intaglio patterns of intaglio modules containing encoded data according to specific encoding symbols, the decoding of which, together with measured tone values for tiny shifts around their positions at decoding stage on a digital image of said intaglio patterns in correlation with said symbols, provides a robust and precise estimation of a register error between modules of distinct tones, thus allowing to easily detect any fake marking obtained via offset printing, even with a smartphone.

The invention relates to a security marking printed via intaglio process, corresponding engraved intaglio printing plate, and methods and devices for producing, encoding/decoding and authenticating said security marking. The security marking comprising multitone 2D intaglio patterns of intaglio modules containing encoded data according to specific encoding symbols, the decoding of which, together with measured tone values for tiny shifts around their positions at decoding stage on a digital image of said intaglio patterns in correlation with said symbols, provides a robust and precise estimation of a register error between modules of distinct tones, thus allowing to easily detect any fake marking obtained via offset printing, even with a smartphone.