Many laser printers encode the date and time on every page printed as well as their serial numbers as a measure to prevent counterfeiters.
Electronic Frontier Foundation manged to decode the code that laser printers print on every page. The Secret Service admitted that they encode some data in printed pages, but until now no one knew what data it was.
Every laser-jet color printer from Xerox, Canon, Hewlett-Packard, etc. prints a color code on every page printed which is composed of the date and time of the print as well as the serial number of the printer. This method was imposed by the Secret Services in order to prevent eventual counterfeiters.
This code is printed through tracking dots that are yellow in color and very small, and are repeated throughout a document. In order to see a them, the dots must be viewed under a magnifying glass or microscope, as EFF revealed.
“So far, we’ve only broken the code for Xerox DocuColor printers,” EFF staff technologist Seth David Schoen said in a statement. “But we believe that other models from other manufacturers include the same personally identifiable information in their tracking dots.”
Here is a list of printers that print and printers that don’t print these tracking dots.
“This technology makes it easier for governments to find dissenters,” said EFF Senior Staff Attorney Lee Tien. “The logical next question is: what other deals have been or are being made to ensure that our technology rats on us?”