Is Your Printer Spying On You?

Is your Printer Spying on you

Is Your Printer Spying On You?

Did you know that many color laser printers print tiny, nearly invisible yellow dots in a pattern that identifies the printer that printed the output?

Yellow Dots(photo from Wikipedia)

I’m not joking and this isn’t something out of some SCI-FI movie, this is real life and it has been going on for many years. It is known as Machine Identification Code (MIC) and it is basically a digital watermark that certain color laser printers and copiers leave on every single printed page.

MIC was developed by Xerox and Canon in the mid-80s and became public in 2004.

The dots are near impossible to see with the naked eye, but under the most basic microscope and even a magnifying glass, they become visible. To you and I, they are just random little yellow dots, but they actually can be decoded and when decoded they identify the device that printed them.

They were originally designed to stop people from using color laser printers to make counterfeit money. There is actually a U.S. Patent (No 5515451) for this purpose. But since they have become publicly known, privacy advocates fear that they can be used to track down someone for other purposes. In fact, the privacy group Electronic Frontier Foundation (EFF) encourages people to send in sample printouts so they can keep a database of devices that print these yellow dots, to help consumers avoid these devices.

In 2018, scientists from TU Dresden developed and published a tool to extract and analyze the steganographic codes of a given color printer and subsequently anonymize prints from that printer. The anonymization works by printing additional yellow dots on top of the Machine Identification Code. The scientists made the software available to support whistleblowers in their efforts to publicize grievances.

MIT students are getting involved in the campaign against the dots with the new Seeing Yellow project.


Source –
List of printers that do NOT display the yellow dots –
EFF website