In one embodiment, a security label comprises a random arrangement of printed LEDs. During fabrication of the label, the LEDs are energized, and the resulting dot pattern is converted into a unique digital first code and stored in a database. The label is then attached to an object to be later authenticated, or the LEDs are printed directly on the object, such as a passport, license, bank note, certificate, etc. For authenticating the object, the LEDs are energized and the dot pattern is converted into a code. The code is compared to the first code stored in the database. If there is a match, the object is authenticated. The label may also have a printed second code associated with the first code, and both codes must match codes stored in the database for authentication. The general shape of the printed pattern may convey the proper orientation of the pattern.