Yellow Dots of Mystery: Is Your Printer Spying on You?

Picture of Yellow Dots of Mystery: Is Your Printer Spying on You?

Imagine that every time you print a document, it automatically includes a secret code that could be used to identify the printer -- and, potentially, the person who used it. Sounds like something from a spy movie, right?

Unfortunately, the scenario isn't fictional. Most color laser printers and color copiers are designed to print invisible tracking codes across every single printed page of their output. These codes reveal which machine produced a document and, in some cases, when the document was printed or copied.

In this instructable, we'll describe three different ways to see the tracking dots your printer produces: with a blue light, with a microscope, or with a scanner. If you don't have the necessary equipment for a particular step, go on to the next one.

For further information, or to share your findings, please visit us at http://www.eff.org/issues/printers.

Want to help? Download test sheets at http://www.eff.org/wp/investigating-machine-identification-code-technology-color-laser-printers#help
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Step 1: Print a page with text/graphics

Picture of Print a page with text/graphics

Print out a page from a color laser printer. The page should use color and have some text or graphics on it. You can find a list of printers that we know print tracking dots at our website.

As you're looking for the dots, keep in mind that they're printed in a regularly repeating pattern across the entire page (not just in the corner of the page), and will be intermixed with other printed data.

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Its cool :)


It's the illuminati, I told them, they never listened. I also don't trust toasters, they probably put crazy tracking sh*t in them too.
thermallyme2 months ago

Its striking :)


devicemodder7 months ago

what's with all the bots here? their accounts advertise insurance and cruise websites. they are the ones with single word comments and comment the same stuff on other 'ibles.

yieldlymph8 months ago


Colonel Hogan9 months ago

this is like the NSA spying on our phone conversations

his is wrong in so many ways and quite disturbing as well come to think of it...

Thats sweet

his is wrong in so many ways and quite disturbing as well come to think of it...

mousepaper1 year ago

Its fabulous :)

Its nice

Thats remarkable

fastbobble1 year ago

Thats astounding

gorgeddamp1 year ago

Thats astounding

Its extraordinary

illrings1 year ago

Thats cold

airbugger1 year ago


Its extraordinary

headlymph1 year ago


tealrink1 year ago


Thats magnificent...

harechubby1 year ago



calmlunch1 year ago


spewlocks1 year ago


clapfilk1 year ago



Its nice

Thats hip

bearblue1 year ago


bearblue1 year ago


gazumpglue1 year ago

Very weird and strange.

Very weird and strange.
BunnyRoger1 year ago
Scary facts.
This is wrong in so many ways and quite disturbing as well come to think of it...
MAApleton1 year ago
I find this just a tiny bit silly, or it it just me?
jillef1 year ago
What about scanned documents? If a document if scanned from any scanner and then saved as a jpeg and sent as an email where the IP cannot be tracked is there any data that can be found then on those jpegs?
Thank you so much :) You made my day !!
heckstallw2 years ago
Its usful
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