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.

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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.

ash? Then why does my binary translator says you are Ò ?
11010010110 --> 10100101 --> A5 (hex) --> A5h --> Ash
Nice! Why do you trim the "1" and "10" though? Signal start/end?
I know of at one count of the operator being identified and convicted by comparing the operator log with the time stamp in the code. I serviced one particular color printer that included firmware to recognize currency. We were warned, sternly, during training that we should NOT attempt it. The instructors stated that they did not know how the firmware worked or how it affected the printer. Since it was a network printer it had the capability of reporting such attempts.

I typed that link freehand, but it probably works
Not only that, even my scanner (canonscan lide 90) can't scan currency (tried it Euro). What is the logic in that??? So I can't send pictures of money? I should return it to the shop.
wow ! this story with firmware just shows how the _government_ is paranoid what make and model is that printer ?
Xerox - I worked for them 33 years. The technology is used in mostly color and all models have something similar. The quality was so good that copies would be accepted by scanners. Something had to be done to prevent counterfeit.
Yes, So smash your printer with a hammer, and print at the library. Except it's still an invasion of your privacy.
However if you send in your warranty card, your privacy would be compromised. Your choices. Rick that the product you buy isn't a lemon, and don't send in the card. Protect you pocket book, by risking your security. Today merchandise can be trace from factory to retailer. Not a stretch to imagine the trace from retailer to purchaser. I fail to trust that every bar coded item I purchase is not link to my checking and/or CC accounts. Paranoia? Perhaps, how can we know for sure?
bar codes are not an issue - they are the same on all stuff of the same type you'd better go google on RFID :) many new printers come now with online registration feature in the setup wizard. im sure this registration includes serial # of the printer and some data from the computer we have one such printer / scanner combo from HP and the thing is quite annoying (with options only 'now' and 'later' and cannot be disabled. it gets back to startup when you use the scanner)
So, invading your privacy is ok, since you've go nothing to hide, right? I'll be sure to hack instructables to get every thing I need to know about you to eliminate your intellectual life, get you locked illegally in a government facilty, And have your family and friends searched and bugged. Still Sound like a good Idea?
It's very different actually. Just because we are all spied on while surfing the Internet in the name of security, does not mean that should spread to any other area's of our lives. It is outrageous.
Grimmiger3 years ago
I just love how so many people are getting paranoid about the government watching everything we do and print!
It is not for that.
It is mostly used with services such as law enforcement to be able to identify if a certain note or letter was printed from a certain suspects printer. Also it allows other agencies to determine if it is actually from where the letter says it is from.
Think of it as more of a personalized watermark.
Please do not reply to this comment if all you have to say is the government are out to get us.
vov35 Grimmiger2 years ago
Law enforcement isn't the government or anything.
the government are out to get us
nate1215 years ago
this is creepy however these were made to stop store cleaks can easialy cheak to see if fake. and kids do this alot they print off a few dollars and spend em at the mini mart.
Yes, yes. Many the time has been when I've seen kiddies at the minimart buying skittles and beer with fake money. WTF, dude? You can't just pull this stuff out of your arse.
well, now, by your own admission..... maybe you can ;) lol
yea, cause I'm sure that a clerk who isn't able to identify a fake by the texture of the paper (or by the hundreds of other techniques used by mint to show that money is authentic) would DEFINITELY know how to look for little dots to see if it was made on a color printer. The dots are not intended to stop counterfitters, they are more likely intended to track down people who write bomb threats, ranson notes, etc. Those may be good things, but it's still an invasion of privacy.
Yea, that seems more likely, to track down printed threats of some sort.
Right in that paper money isn't printed on paper, the texture will be the first tip off something is hinky. No doubt there are those that may go through the process to use a paper that's similar to the feel of legal money. But only counterfeit large bills would make that worth the effort. Large bills get closer scrutiny by a clerk, so the chance of getting caught is greater.
hmmmmm your right however some peopl are pretty stupid.
seems logical ...and was my first thought..but the dots may not fit on a bill and only partially...but i dont know how far apart the dots are ..out of curiosity i am going to look into it more
beehard443 years ago
what if you have black ink?
RN13584 years ago
 I have been servicing copiers and printers for over 30 years (unfortunately). The yellow dots you are talking about are there to prevent counterfitting, not so much for currency, but for Stock certificates, Bonds, etc. I have been told by several manufacturer's reps that the yellow dots are required by the government, but I have not been able to verify that as fact. As for the comment that "your printer is spying on you", Canon, Xerox, Minolta, etc. couldn't care less what you copy...they just want to sell more printers, copiers and supplies! Most newer color copiers also will detect if you try to copy currency, and prevent it from printing out. One model I use to service would generate an error code that had to be reset by the tech if you tried to copy currency; another model would display a warning the first 2 times you tried to copy currency, and on the third attempt, the machine would be disabled, and would require the replacement of a very expensive main pcb to fix the machine. And, of course "nobody here tried to copy money" was the first thing the customer would say!
djr6789 RN13584 years ago
i tried making giant a4 sized £10 notes and my printer stopped working :O and now i know why :O
zomfibame5 years ago
Just a very simple, basic question for you guys; the identification dots printed on home printers..... are they all yellow, in every brand of printer? because if that is the case then... why can't one just adjust the yellow ink 100% down in an expensive printer, and in a cheap one where you can not adjust the percentage of each ink color.... just remove the yellow ink container. If a person wanted to make political publications, I'm thinking that the lack of yellow ink would become a political statement in and of itself; wouldn't it? If the publication had only red, purple, blue, and black, but NO yellow, and as a result, no green.... then that itself would be a political statement. so, like I said, why not just "turn off" the yellow ink? ohhhh, and also, Is there anything at all that I own that the government can't track? hummm, I wonder if they can track my toilet-paper too?
i think that if the printer "decides" to add the dots without your order.. even if you set the yellow settings to 0%, it would still print the dots, even with your specific order.. it would be best just to remove the yellow ink container.. in my hp its not possible to do, since the yellow is together with the magenta and cyan..
A typical color laser printer will not print with one of the cartridges missing. Empty, yes, missing, no.
just replace it woith a different colored empty cartridge!
That would be the same as it being missing, color laser printers can identify whether the cartridge installed is t he right color and won't print if the correct color cartridge is not in every slot. Older models might still print, but most color lasers have been able to identify the cartridge for several years/generations. I checked a website to see if mine was known to do the yellow dots and it wasn't listed because it was too new, but the 2 or 3 prior models from years past that it is based upon are on the list.
Icalasari ac-dc4 years ago
Best solution would be to print using a yellow sheet of paper
Actually, it would be best to just melt shut the opening on an almost empty cartridge; now days, most colored inks come in one cartridge that has the three base colors in it.
Actually, this topic is about color LASER printers and copiers, there is no opening to melt shut, and on many color inkjets the print head is not part of the cartridge anymore so you'd be destroying a part you need to reuse.

The best solution is don't be doing anything that would get your government curious as to who printed something, remembering it means nothing for them to have the dots, they'd also already have to be investigating you to compare YOUR printer to the dots.  The dots themselves may tell them what make/model of printer printed something but not who owns it till them match it up.

Obviously only matching up you as the owner of a particular printer is not conclusive evidence by itself since other people own the same printer, but nevertheless if you're paranoid about being traced back to something you print, the best solution is don't print it at all - or if you must, not on your own printer.
Nyxius ac-dc4 years ago
If they have your serial number from something you printed, then all they have to do is check with to the company that manufactured the printer .  Most people have to register there printer to activate the warranty, and if you've registered then you're traceable.
ac-dc Nyxius4 years ago
That's silly. I've been in the tech business for 20 years and have never "registered" a printer, laws in the US do not allow a warranty to be less than stated on the label if you merely didn't register it.

"Registering" a product is mostly about submitting your email address for spam.

Under NO circumstances is a warranty ever subject to registering it when it was advertised at the time of sale.  Never, ever, this is clear contract law, it would have to be specified as such which no consumer would agree to.

Well, I mean the port that allows the ink out of the cartridge. I also said "nearly empty". If you did it to just that part, or stopped the ink from coming out some other way, it would be OK.
I suspect you need to learn a bit more about laser printers and consider the context.

Remember for one, it's a color laser printer expressly because you want to be able to print color, nobody wants to swap cartridges around unnecessarily, nor damage one by trying to block it, and some printers won't even print with empty cartridges in them (actually most won't).

You could easily damage the printer, or a cartridge worth over $100.  You almost certainly would trying to prevent toner from coming out, and most printers these days are smart enough, optical sensors for print quality and calibration purposes, that it wouldn't even print until you corrected the fault condition.

The real question is why?  Why bother? It is not some challenge you need to try to do, it is a relatively pointless to even try because if someone is up to something that might get them into trouble, it is no hard thing to simply print on a printer that isn't traceable to them, or after printing such an ultra-secret and dangerous page simply wipe down the printer to get rid of fingerprints and throw it away in a trash bin somewhere.

It's a bit like wearing a tin-foil hat, people are not needing to be paranoid, not needing to do anything about it, just a bit of a news item that it was doing that when most people didn't realize it.

Most people don't realize scanner drivers have code in them to detect US currency either, and there's nothing to be concerned about unless someone is up to no good and gets caught.

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