Federal contractor Reality Leigh Winner was arrested on charges of leaking classified material and sentenced to five years in federal prison in 2018. What led to her arrest was the hidden yellow dot ID pattern technology on the color laser printer she used to print out the documents. The primary reason for the dots is purportedly to help the Secret Service in counterfeiting cases. Color copiers and laser printers became so good at reproducing colors that they became a tool for counterfeiters some time ago. Not all color copiers and laser printers print the dots, but for obvious reasons, the printer manufacturers and law enforcement don’t generally acknowledge which printers do and which ones don’t. When decoded, the yellow dots can indicate the make, model and serial number of the printer and, in some cases, the date and time. With this information, law enforcement can potentially track down the owner of the printer by following the serial number from the manufacturer to the reseller and then to the purchaser. By design, it’s nearly impossible to see the dots with the naked eye, so you’ll want a way to magnify any page that you want to inspect. Using a microscope or magnifying glass with magnification power of 10x or better to view a blank part of a printed document should allow you to see the dots, if they exist. If you want to make it easier, use a bright blue LED flashlight in a dark room, which should turn the yellow dots a dark blue or black. If you have a good quality scanner and a graphics program that can zoom and invert the colors, you can also find the pattern, which should repeat itself throughout the page. The EFF has published a list of printers that it says do and do not display the tracking dots, but it’s neither up to date nor is it a complete list.
