Maya Embar’s research while affiliated with Illinois Institute of Technology and other places

Most color laser printers manufactured and sold today add "invisible" information to make it easier to determine when a particular document was printed and exactly which printer was used. Some manufacturers have acknowledged the existence of the tracking information in their documentation while others have not. None of them have explained exactly how it works or the scope of the information that is conveyed. There are no laws or regulations that require printer companies to track printer users this way, and none that prevent them from ceasing this practice or providing customers a means to opt out of being tracked. The tracking information is coded by patterns of yellow dots that the printers add to every page they print. The details of the patterns vary by manufacturer and printer model. In this document, our team will discuss several obfuscation methods and demonstrate a successful one. Included in this document is an explanation of the firmware generated yellow dots matrix and answers to the following questions: 1. Which printers produce the dots? 2. How are the dots put on? 3. What is needed for testing? 4. What is the dot size and spacing? 5. Where are the dots located on the page? 6. How can the dots be rendered useless?