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EFF exposes laser printers' hidden secret code

Written by James Delahunty (Google+) @ 20 Oct 2005 3:40 User comments (14)

EFF exposes laser printers' hidden secret code The Electronic Frontier Foundation (EFF) has managed to crack a secret printer code with the Xerox DocuColor line of laser printers that allows the U.S. Secret Service to track down individuals who produce counterfeit documents. While it was a known fact that the U.S. Government had an agreement with several major printer manufacturers (including Xerox, Canon and others), the extent of the information that can be read from a secret code was never disclosed.
"We've found that the dots from at least one line of printers encode the date and time your document was printed, as well as the serial number of the printer," said EFF Staff Technologist Seth David Schoen. The serial number of the printer could be used to track the customer who bought it. The code is a series of dots printed onto the pages. The dots are yellow and less than one millimeter in diameter but can be seen on the pages.

A blue light, magnifying glass or microscope can be used to see the dots properly. The manufacturers never really say anything on record about the code but this is what was said to OUT-LAW Magazine earlier this year: "Epson is cooperating closely with industry groups and the relevant authorities in each country to prevent counterfeiters use [sic] its products in illegal activities. However, due to the sensitive nature of this issue we are unable to comment about the exact measures that are being taken."

If you want to check out how to read the dots yourself, there is a very interesting article provided by the EFF. You can view that by clicking here.

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14 user comments

120.10.2005 7:47

Heh, never knew that!

220.10.2005 9:03

Man, I saw a thing about this on court TV years ago. They tracked some guy who murdered someone based on the note he left. They were saying that every printer prints something like this, a dot, that has all the information about the printer on it. So they tracked down the original printer and printed a test page to see if the two dots matched up, and they did.

320.10.2005 9:37

The EFF website ( is fascinating!

420.10.2005 12:41

big brother.. lol.. someone active in that type of activity shouldnt use devices that go online

520.10.2005 12:57

I will seriously think twice about sending out any threatening letters again. Thanks AfterDawn for this info ;)!!!

620.10.2005 13:20

Im a tech that works in that industry and It is true, All copier manufactures do this on every piece of paper that comes out of a color copier.

721.10.2005 10:08

This only effects LASER PRINTERS......not ink printers.

821.10.2005 10:15

Quick! Back to dot-matrix printers... Shall anyone capable(s) has to investigate further for the rest of commercial equipment?

921.10.2005 17:46

RATS..........guess I'll have to buy another laser printer with all that money I printed? (JOKING, of course!)

1022.10.2005 11:46

...going to connect my still working dot matrix

1122.10.2005 14:10

wow this article is cool,secret codes in printers not thats wierd

1222.10.2005 15:26

wow but doesn't this invade your personal privacy i thought the privacy act of 96 clearly states without a warrent they are not allowed to search any device related to bussinesses and home systems and services so looks like the us goverment lied again also just unplug the phone line to the printer and how will they be able to tell duh

1324.10.2005 1:21

It has not got any personal info printed about yourself, it has the id of the printer and s/n etc.... Then from the s/n they will be able to narrow it down to where you bought the printer from, then if that store took your deatails they may be able to hand it over to the authorities or they could check CCTV : ) That is of course you have created illegal documents of some sort, or counterfeit money and is cought by someone.... If you read the article they dont sent any info via the telephone line... Also not every one has a "fax" printer... : )

smoke me a kipper i'll be back for breakfast - Ace

1431.10.2005 13:25

Screw the "privacy" crap - is the GUBMENT gonna pay for my ink/toner????

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