Is Your Printer Spying on You?

Category: Printing , Privacy

I've heard that some printers embed a secret coded dot pattern on each printed page, and that if you decode the dots, you can determine the owner of the printer and the exact time the page was printed. That sounds like a privacy violation -- is it true?

Even Your Printer Has DNA

Yes, it's true. In an effort to snare counterfeiters, the US government has persuaded some color laser printer manufacturers to encode each page with identifying information. The EFF (Electronic Frontier Foundation) has recently proven what many have suspected for a long time - that at least some laser printers embed a secret machine identification code on every page they print, which reveals when the page was printed, and the serial number of the printer on which it was printed.

You might might not think it's a big deal that your printer's serial number is embedded on every page. But if you registered your printer with the manufacturer when you bought it, the manufacturer knows that you are associated with that printer's serial number. In a recent article, the Internet Patrol mulls the disturbing potential impact of this.

The EFF's Machine Identification Code Technology project, which has been investigating this for some time, has released the results of their success in identifying the hidden machine identification code which is printed by a Xerox DocuColor color laser printer. The results are startling, and troubling, and sure enough, the code is there. It looks like a bunch of yellow dots - a sort of printer braille, but if you know how to read them, they clearly translate to the date and printer serial number.

You can see the EFF's machine identification codes at their Machine Identification Code Technology project site.

Explains the EFF, "Imagine that every time you printed a document, it automatically included a secret code that could be used to identify the printer - and potentially, the person who used it. Sounds like something from an episode of "Alias," right? Unfortunately, the scenario isn't fictional. In a purported effort to identify counterfeiters, the US government has succeeded in persuading some color laser printer manufacturers to encode each page with identifying information. That means that without your knowledge or consent, an act you assume is private could become public. A communication tool you're using in everyday life could become a tool for government surveillance. And what's worse, there are no laws to prevent abuse."

Bad Kitty!

If you find this story interesting, and you have a Lexmark printer, you should read about the Lx-CATS spyware that comes free with certain Lexmark printers.

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Most recent comments on "Is Your Printer Spying on You?"

Posted by:

HP Drifter
20 Oct 2005

MS Word and perhaps other software writing apps leave *footprints* of a kind as well i'm told.

EDITOR'S NOTE: Sure, just open a Word file with Notepad and you'll see that the author's name is hiding in the gobbledygook. Microsoft has added a feature to Word that will remove personal information from your document when you save it:

1. Click on Tools / Options
2. Click the Security tab
3. Under Privacy Options, select the box next to "Remove personal information from the file on save"

Posted by:

Bob Deloyd
21 Oct 2005

I don't like things done behind my back or put on my computer without my knowlage. I hated that Lexmark printer I bought a few years ago. It was always trying to connect to the internet and I blocked it with my firewall. Ended up giving it to a friend. Now I have a HP laser printer and love it! But after reading this column, I just won't print any counterfeit bills or send out that occasional ransome note! //bob

Posted by:

Bob Dwyer
21 Oct 2005

As it happens those code marks were how the police identified the BTK serial killer.Both the Defense Dept and the FBI have used them numerous times in identifying would be spies and others who illegally copy classified documents.
It involves a lot more than counterfeit money

Posted by:

21 Oct 2005

Got a Epson Stylus in which I've had to cripple a few of the modules in the drivers for the printer because they was always phoning home. Printer works just fine without them.

Posted by:

21 Oct 2005

CSI had just such a show not too long ago, where a document was identified by the machine it was copied on. That information found in the document proved that a individual at a Zoo was involved in a killing.
They didn't mention if it was a color printer..... and I got the impression is was only a black & white printer. I guess they knew about the serial number & date thing and applied "poetic license".
How about that!

Posted by:

Rei Hikari
21 Oct 2005

It's true. I have a Magicolor 2300w from minolta and IF you print in color, tiny dot patterns can be seen when viewed under blue light (UV doesn't work). The yellow toner isn't obvious and transmits almost as brightly as the paper itself in white light, but in blue light its as visually heavy as a brick and is hard to miss if you look close. I used a microscope for a sample image, but you can see them with your eyes if you don't have bad vision.

Posted by:

23 Oct 2005

To me this is funny because I have been using "invisible" writing for years in email and when it is printed on paper you still cannot read it unless you change the print colors before you print. It is still there on the paper in a gray tone so light (254), your eyes cannot see it! Can't put an example here though.

EDITOR'S NOTE: Cool, send me an example and I'll link it in here.

Posted by:

24 Oct 2005

The problem with this technology, like anything else, is that the people who its designed to catch will ultimately figure out workarounds to avoid leaving the fingerprint. So the rest of us will find ourselves victims of unauthorized government intrusion while the bad guys do not.

Posted by:

28 Oct 2005

I agree, the bad guys simply won't register or will register it under a false identity. It's like them making all .us domain owners show all of their personal information to the internet world.
All it's doing is taking away the ability for the good guys, who do follow the rules, to protect their own identity. It's awful.

Posted by:

26 Sep 2007

This site linked in the "Bad Kitty" section above,, is a linkfarm (with popup ads that can defeat some popup blockers, too). There is no real information there, just a bunch of links to googlesyndication ads. This particular linkfarm interface has become fairly standard (tho is most often seen on squatted domains) and is clearly good enough to fool some people who ought to know better ;)

Posted by:

Mark Thomas
25 Oct 2007

I am involved in a situation at work where I suspect that a document was produced by someone other than the person who is claiming to have produced it. I have documents that I know were printed on the suspected authors printer/ fax machine, a black and white printer. I am not very technically skilled, but I wonder if anyone can tell me about a service where I could sent these documents to be compared?

EDITOR'S NOTE: Sounds like FBI-type stuff. I don't know of any service like that, but others here can chime in...

Posted by:

20 May 2009

Do any black & white laser printers embed codes.

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