A system for authenticating an object includes a label (12) with invisible indicia (14) on the object which rotates a polarization of incident light; a digital camera (18) having a light source (20), an image sensor (22), a first polarizing filter (24) having a first orientation, and a second polarizing filter (26) having a second orientation orthogonal to the first orientation; illuminating the label with light from the light source through the first linear polarizer; forming an image with the image sensor using reflected light from the label wherein the reflected light passes through the second polarizer prior to reaching the sensor; wherein the second linear polarizer makes the invisible indicia visible; and authenticating the object.