According to seeingyellow.com and the Electronic Frontier Foundation most color printers print a hidden series of yellow dots that create a unique “fingerprint” and could be used to track your individual printer. This could then be used for counterfeiting or other criminal investigations to link pages printed back to you and your printer, so you might want to think twice before mailing in your product registration.
According to seeingyellow.com:
Most color laser printers made and sold today intentionally add invisible information to make it easier to determine where (and when) a particular document was printed. This seems to have been done as part of a secret deal between the United States Secret Service and the individual manufacturers. Some of the manufacturers have mentioned the existence of the tracking information in their documentation, and others haven’t. None of them have explained exactly how it works or what information is conveyed. No law requires printer companies to help track printer users this way, and no law prevents them from stopping this practice or giving customers a solution to avoid being tracked.
When you print on a color laser printer, it’s likely that you are also printing a pattern of invisible yellow dots. These marks exist to allow the printer companies and governments to track and identify you — presumably as a way to combat money counterfeiting. When one person asked his printer manufacturer about turning off the tracking dots, Secret Service agents showed up at his door several days later.
This information is most famously known to be coded by patterns of yellow dots that the printers add to the background of all the pages they print. The yellow dots are hard to see with the naked eye, but can be seen under bright blue light or with a microscope. Their arrangement reveals which printer was used to print a particular document, and sometimes also shows when it was printed. Some of the codes have been understood while others are still mysterious, but none of the printer manufacturers has denied that the dots are intended to help track a particular document to a particular printer (or that they can actually be used for this purpose). This is a direct attack on the privacy of the owners and users of printers, and in particular, on their right to free, anonymous speech.
Printer companies still seem to be unaware that their customers are concerned about this attack on privacy. We’d like to change that by encouraging the public to call in and ask how to disable the tracking. Hopefully, some of the manufacturers will be willing to do the right thing for their customers and make a solution available to stop the tracking.
How to See the Dots
Tracking dots are usually invisible to the naked eye under normal light. They are tiny and light yellow which makes them hard to see against the white of a page. They are usually printed across the entirely of a page — even the parts where that are otherwise blank. They are present in both color printers and copiers but do not show up in pages printed in black-and-white mode.
The best way to see them is by using an intense blue LED in a darkened room. You can frequently find appropriate blue LEDs as keychain mini-flashlights.
You can also see them simply by using a high resolution flatbed scanner. The images below were scanned at 600dpi. Zooming in should reveal the yellow dots when they are present. To make them more clear, you can use photo manipulation software (like the freely available GIMP or Adobe Photoshop) to show only the blue channel of the image where the dots will be more visible.
According to EFF:
The ACLU recently issued a report revealing that the FBI has amassed more than 1,100 pages of documents on the organization since 2001, as well as documents concerning other non-violent groups, including Greenpeace and United for Peace and Justice. In the current political climate, it’s not hard to imagine the government using the ability to determine who may have printed what document for purposes other than identifying counterfeiters.
Close up of actual tracking dots, taken through a microscope from EFF.
List of printers according to the Electronic Frontier Foundation:
The list includes printers from Brother, Canon, Dell, Epson, Fuji, Hewlett-Packard, IBM, Konica, Kyocera, Lanier, Lexmark, Minolta, OkiData, Panasonic, Ricoh, Samsung, Savin, Tektronix, Toshiba, and Xerox.