A method and system for identifying, tracking, and/or authenticating objects that is simple to apply and to use by an intended user, but is extremely difficult to counterfeit or compromise by an unintended user. Also disclosed is a multi-color, co-planar indicium made of a combination of printed patterns of multiple inks. The printed patterns may be modified by software-generated masks to ensure that the patterns are co-planar. The indicium is undecipherable unless irradiated with specified wavelengths of light radiation, filtered through specified spectral filters, and read and decoded by an electronic image reader. The indicium may be visible or covert. The indicium encodes unique true information about the object and may encode nonsensical or intentionally incorrect information as a further deterrent to unauthorized use. The method permits the indicia to be applied to objects at high processing speeds possible with inkjet printing.