Your printer is spying on you

Your printer is spying on you

It happened on June 3 in Augusta, Georgia. FBI agents arrived at the home of 25-year-old Rialiti Lee Winner to arrest her.

The FBI concluded that Winner, an employee of the international corporation Pluribus, who worked under the contract for the US National Security Agency (NSA), issued a secret document from a government agency and passed it on to the Intercept news site.

Many color printers add dots to printed documents, and people don’t even know about it. In affidavit, FBI officials claimed that Winner admitted to printing a secret report from the National Security Agency. Rialiti Lee Winner was arrested on charges of stealing secret documents.

Here’s what these tags look like:

After this information became public, the experts took a closer look at the ill-fated document posted on the Internet.

They found something interesting: yellow dots, forming a rectangular pattern, repeated from page to page.

The points are almost invisible to the naked eye, but their presence is quite obvious.

Further research revealed that this “pattern” carries information about the exact number and time when the pages were printed: 6 hours 20 minutes May 9, 2017.

In any case, it should be the time that the printer’s own clock showed when it printed these pages. In addition, the dots are encrypted with the serial number of the printer.


FLORIAN HEISE / WIKIPEDIA. Points applied by HP laser printer are especially noticeable in blue light.

Security experts (as well as human rights defenders) are, of course, aware of the existence of these micro points. Many brands of color printers add them to documents, and people don’t even know about it.

The Electronic Frontier Foundation website has an online tool to help you understand what information your printer has encrypted.
In our case, the FBI did not officially confirm that microdots were used to identify the suspect, and the organization refused to comment on this article.

The US Department of Justice, which issued a statement about the charges against Winner, also refused to enter into details.

The Intercept site statement alleges that “Winner has filed charges that have not been proven. The same can be said about the statements of the FBI about why the bureau decided to arrest Winner.”

One way or another, the presence of microscopic points on a secret document, which became (against the will of the NSA) public property, has aroused genuine interest.

“When we zoom in on photos, they are clearly visible,” says Ted Heng from Document Cloud, one of the first to notice the dots. “It's interesting and quite remarkable that such things are used.”

Another expert, Rob Graham, published a post in his blog explaining how to find and decipher microdots.

Based on their location relative to the overlay stencil, you can determine the hours, minutes and date, as well as the printer number. Several experts, deciphering the points on the document, got the same result.

Microdots are used for quite some time. The American human rights organization Electronic Frontier Foundation (EFF) (founded to protect the rights enshrined in the Constitution and the Declaration of Independence due to the emergence of new communication technologies - Approx.translator), compiled and constantly updates the list of color printers using this technology.

The photos below, provided by the EFF, show how to decipher these points.


ELECTRONIC FRONTIER FOUNDATION / CC BY 3.0, Yellow dots, magnified 60 times, were found on the printed pages of a secret document


ELECTRONIC FRONTIER FOUNDATION / CC BY 3.0. The dots become much more visible if the photo is enlarged and illuminated with a blue LED flashlight.


ELECTRONIC FRONTIER FOUNDATION / CC BY 3.0, To make it easier to see, in this photo points are specially highlighted. What does this pattern mean?


ELECTRONIC FRONTIER FOUNDATION / CC BY 3.0, the location of the points allows you to find out the time and date of printing, as well as the serial number of the device

Microdot technology, in addition to being used in espionage, can potentially be useful for other things, said Tim Bennett, an analyst at consulting software firm Vector 5, who is also interested in the history of the NSA secret document.

“You can use the knowledge of how microdots work to protect yourself from fakes,” explains Bennett. “For example, you get a document that claims that it was 2005 - but in fact [judging by microdot] several months".

Just in case, keep in mind: if you ever need to understand what the dots on any important document mean, the Electronic Frontier Foundation website has a special interactive tool for this.

Hidden messages

Similar methods of steganography — secret messages hidden in public view — were used long ago.

Take at least secret patterns on banknotes designed to combat counterfeiters: the notes of many world currencies carry a strange pattern, like a constellation.

Many scanners and photocopiers are programmed to recognize this pattern and do not allow copying banknotes.

In the US National Security Agency itself, there is a historical example: during World War II, German spies in Mexico City used microdots, placing secret reports on the inside of envelopes sent to Lisbon.

Spies requested radio equipment and other special equipment from Germany. The Allies intercepted these letters, and the operation was foiled.

The microdot, which the Germans used, were in fact in no way encrypted text, just very tiny.

This kind of communication was widely used during the Second World War as well as the Cold War. It is said that Soviet agents operating in West Germany used caches to transmit their micro-messages to Moscow.


WIKIPEDIA, Microdot on the inside of an envelope sent during World War II by German spies from Mexico City to Lisbon

Today, many companies offer to use microtext to protect your property. They sell bubbles with fast freezing liquid containing microdots where some data is encrypted - for example, the serial number of your laptop.

If the police find a stolen item, marked in this way, then theoretically it will be able to find out who was its real owner.

In some of its forms, steganography does not even use letters and numbers. Alan Woodward, a security expert at the University of Surrey, cites as an example SNOW (abbreviated Steganographic Nature Of Whitespace, literally “the steganographic character of the gaps”) when non-printable characters are used within a particular text — space, line feed and tabulation.

A certain number and order of these spaces, "empty spaces", can carry an encrypted invisible message.

"Trying to detect these gaps in the text is like searching for a polar bear in the snow," they vividly explain on the Snow website.

More than 45,000 complaints were received against printer manufacturers whose devices are micro-dots.
In general, as Woodward points out, there are many ways to track who exactly printed the documents or accessed them.

“Organizations like the NSA keep records of each case of a printout of something, not to mention the use of different methods of tracking printed documents,” he says. “They certainly know that people know about the yellow dots, so they don’t rely only on them. "

About ethics of accession by the printer of certain information to the printed document without the knowledge of the printout has long been heated debate.

The opinion was expressed that this is a violation of human rights, and one of the research projects of the Massachusetts Institute of Technology received more than 45,000 complaints about the manufacturers of printers whose devices are applying microdots.

And yet, as many believe, such hidden security measures that ensure the secrecy of important documents are preserved in some cases are fully justified.

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  • Your printer is spying on you

    Your printer is spying on you

    Your printer is spying on you

    Your printer is spying on you

    Your printer is spying on you

    Your printer is spying on you

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    Your printer is spying on you

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    Your printer is spying on you

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    Your printer is spying on you

    Your printer is spying on you

    Your printer is spying on you

    Your printer is spying on you

    Your printer is spying on you

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    Your printer is spying on you

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    Your printer is spying on you

    Your printer is spying on you

    Your printer is spying on you

    Your printer is spying on you