Since late 2004, EFF has been warning the public about "printer dots" -- tiny yellow dots that appear on documents produced by many color laser printers and copiers. These yellow dots form a coded pattern on every page the printer produces and can be used to identify specific details about a document; for example, the brand, model, and serial number of the device that printed it and when it was printed. In short, the printer dots are a surveillance tool that can link each printed page to the printer that printed it.
To help individuals learn more about printer dots and how to find them, EFF posted a video and tutorial to Instructables, titled, "Yellow Dots of Mystery: Is Your Printer Spying on You?". You can also watch the video here:
Printer dot surveillance is a disturbing end run around individuals' right to anonymous speech. Anonymity is a vital freedom -- it can help political or religious speakers, labor organizers, or whistleblowers avoid retribution for their beliefs and opinions. Around the world, anonymity is an important practical protection for dissidents and religious groups against persecution by repressive governments.
Furthermore, it's deeply troubling that printer manufacturers implemented this surveillance mechanism under the table after secret meetings between government representatives and technology manufacturers. Printer companies don't disclose the tracking to their customers and so the existence of these yellow tracking dots remains secret.
In the meantime, you can do your part by spreading the word about printer dots, sending EFF samples from your own color laser printers, and contacting manufacturers to express your privacy concerns directly through the Seeing Yellow site. And of course, you can support our work on privacy, anonymity, and free speech issues by becoming an EFF member.