Connect the Dots

For years, governments all over the world have secretly been collaborating with the high-end color laser printer industry in order to track the origin of every color copy made. They're doing it by programming the printers to create specific patterns of yellow dots -- not visible to the naked eye -- on every copy. These dot patterns are codes for the serial number, the make of the printer, and possibly even the time and date when the print was made. By cross-checking this information with printer company databases of people who have purchased the printers, federal agents can figure out who made a given color copy (of, say, an antiwar rally flyer) and when.

No, really.

Xerox has openly admitted it shares its customer lists with the US Secret Service if asked. And both the US Secret Service and the Dutch government told PC World in a recent article that they asked printer companies to create the yellow dot patterns to help law enforcement track down counterfeiting suspects. Because color laser copies are so good, counterfeiters frequently use them to create fake money, as well as fake train tickets and other valuable items.

Right now, the system works because most people don't know about it, and you can only see the yellow dots if you look at the paper under a blue light (to highlight the yellow). Generally you need a magnifying glass or a weak microscope too. It also works because color laser printers are high-end enough that most people buy them using credit cards. That's how the laser printer companies generate their lists of purchasers associated with specific printer serial numbers.

Robert Lee, a computer science student, spent the summer after graduating from Yale researching these yellow printer dots, trying to figure out which companies were using them and what they might mean. My coworkers at the Electronic Frontier Foundation (EFF) helped him along, giving legal and technical pointers along the way. The result of two months spent peering at color laser copies with a blue LED was the discovery that only one model in his study doesn't use the yellow dots: the Xerox TekTronix Phaser 7700. But most other Xerox models do, as do all the ones he tested by Canon and Toshiba.

Because so little is known about what the yellow dots mean (aside from containing the make and serial number) and how governments are using them, many disturbing questions arise. For example, how do we know they're only using these printer marks to track counterfeiters? What if they're also tracking people who copy what they think are anonymous political flyers or pamphlets? Or people who post flyers announcing meetings of Muslim groups?

One of the fundamental ways the First Amendment works is by protecting anonymous free speech. These dots undermine your ability to make a color copy anonymously. The government can most likely track the document back to you. Even if you pay cash for color printouts at Kinko's, your purchase or visit to the store will probably be recorded by a security camera. It appears that the dots may contain a time stamp, so it would be relatively easy to cross-reference video of a 5:15 p.m. purchase with some copies made at 5:12.

How can this happen? Shouldn't there be a law? Yes, there should be, but as of now there are absolutely no regulations or laws that stop printer companies or copy shops from giving information about their customers to the government. Phone companies and Internet service providers, by contrast, are forbidden to give the government data about you unless served with a court order. But this isn't true for credit card records kept by laser printer companies. Sure, these companies could demand court orders, but none of them have. Xerox told Lee that it has always been happy to comply with the government when asked for this kind of data.