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Next time you make a printout from your color laser printer, shine an LED flashlight beam on it and examine it closely with a magnifying glass. You might be able to see the small, scattered yellow dots printer there that could be used to trace the document back to you.

According to experts, several printer companies quietly encode the serial number and the manufacturing code of their color laser printers and color copiers on every document those machines produce. Governments, including the United States, already use the hidden markings to track counterfeiters.

Anonymous sez: “The answer to the question of how long color laser copiers have been encoding their serial numbers onto their prints is: at least since 1995 or so.

Original article from Yahoo
Source: Boing Boing