News about the yellow dots on laser printouts

Numerous laser printers print a barely visible code on every page output. Many details of this undocumented monitoring method are still unknown. Today I can present some more information about it and a concrete puzzle.

Deutsche Version

Since the 1990s, numerous laser printers and copiers have added an almost invisible pattern to each printout, in which various data about the origin of the printed document are encoded. The firmware of these devices is responsible for the implementation.

Quelle/Source: Schmeh

The Machine Identification Code

The invisible pattern consists of a dot grid distributed over the entire print field. The dots have a diameter of only one tenth of a millimeter and are spaced about one millimeter apart. Since the marks are small and also printed with a light color (yellow), they are not visible to the naked eye. On a Din-A4 sheet, the code appears about 150 times. This means that the information can be read even if only a scrap of paper is available or large parts of the output are overprinted.

These yellow dots, also known as Machine Identification Code (MIC), were first described in an article in PC Magazine in 2004, which led to widespread media coverage. In the years that followed, numerous experts studied the dot patterns and discovered some details about them. Among them was Cipherbrain reader Peter Buck.

To date, neither a printer manufacturer nor a government agency has ever published anything about this surveillance method. It is also not known if any government agency requires this code from manufacturers. It is possible that the NSA is behind this.

Incidentally, the Machine Identification Code is not to be confused with the digital watermarks on banknotes known as “EURions,” which enable photocopiers and graphics editing programs to recognize and reject the copying of banknotes.

To my knowledge, four cases have come to light so far in which the printer code has presumably led to the conviction of criminals. The first case involves whistleblower Reality Winner, the second an arsonist in Berlin, the third a militant Islamist, and the fourth a sender of threatening letters. If my readers know of any other examples, I would be very interested to hear them.

By the way, the last edition of the program “Aktenzeichen XY ungelöst” showed the following blackmail letter, which was probably created with a laser printer:

Quelle/Source: ZDF

The letter was printed on Kodak Moments photo paper of the type used in the Rossmann and DM drugstores. I do not know whether a printer code is included. I assume that the police have checked this.

New information

A few weeks ago, I received an email from a blog reader named Itermann. As the operator of a copy store, he has been looking into the Machine Identification Code and found out a few new things. You can read about it here.

Especially interesting is the chapter “MICs: Own investigations”. In it, Mr. Itermann reports on numerous documents that he examined for the yellow dots. As expected, the code was far from always present. Apparently, some models print the yellow dots, others do not. Color printers that normally print the code do not do so when operating in black-and-white mode. It is not known if there are other printer codes.

A riddle

Finally, I want to pass on a riddle from Mr. Itermann to my readers. On a laser printout, he found the following pattern of 18 dots (in the original, all are yellow and much smaller), apparently arranged in a 16×32 grid:

Quelle/Source: dys2p.com

The dots probably represent the serial number of the device (JWF11162) and repeat across the page. The pattern does not change with the time, date, or content of the printed document. It is in the shape of a parallelogram tilted at about 30 degrees. The orientation, start and end of the pattern could also be different than shown here.

Other serial numbers of the same printer model are JWF03569, JWF86454, JWF16133, WGR08684 and WGR04248. There are more samples of this type here.

Can any reader identify what is coded here?

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Further reading: Der rätselhafte Quittungscode von Quebec

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