How Your Color Printer Spies on You
Ever had an irresistible urge to scan a US$100 bill and see how close your color printer can reprint Old Ben Franklin's face?
If you can't resist the urge to print counterfeit money, then take my advice and at least refrain from spending the fake US$100. The bill can probably be traced back to you, courtesy of "tracking dots" the printer embeds in each copy it produces.
The dots, which are practically invisible, contain information about the make and model of your printer and its serial number. In some cases, it can even include the date and time the page was printed. They're apparently the outcome of a secret deal between the U.S. Secret Service and printer manufacturers, presumably to help identify counterfeiters.
Of course, not only counterfeit currency can be tracked. Say, for instance, you send an "anonymous" package exposing government corruption to a journalist, with at least one page produced on your color laser printer. If that page ever gets in the hands of the Secret Service, or anyone else who knows how to read the tracking dots, it can be traced back to you.
This kind of surveillance is a direct attack on free and anonymous speech, a right that the U.S. Supreme Court has upheld on numerous occasions. But neither the Secret Service nor printer manufacturers seem to care about the law, although that might change if someone who is harmed due to this technology successfully sues the a manufacturer for damages.
In the meantime, the only way to protect your anonymity if you use a color laser printer is to pay cash for your purchase, never register it with the manufacturer, and never return it for warranty service. That's a stiff price to pay for preserving your right to anonymous speech, but privacy is rarely convenient.