Most printers leave a secret series of yellow dots to allow the government to track any printed paper.
This Has Been Going on for Years
Implemented for Security
Printing has become cheaper than ever before. This means that faking documents has become easier than ever before. Another problem is copyright issues. It was predicted in 1995-2001 around 650 million dollars were lost every year do to printing. Another reason they implemented it was illegal activities. Intelligence agencies were especially eager to start tracking printed document. They have been able to track this ever since
In 2015, due to the freedom of information act, information was released that was released that almost every major company has printers that encode these messages.
Extrinsic Signatures
Extrinsic Signature is when a printer encodes in some way information, including its serial number and the timestamp of when the paper was printed. This is done by changing the printing parameters or simply printing a secret code.
If you look at the top picture, you can see small yellow dots. The pattern of these dots has a code embedded within. Many groups of people are trying to decode these, sadly it is different for every organization.
However, the Xerox DocuColor has been decoded. Their code uses a grid that is repeated with slight variations across the paper, parallel with the sides. This grid is 15 by 8 and holds about 14 bytes of 7 bit information. The information includes the serial number and the timestamp it was printed (down to the minute).
You can find it here
Ways to Avoid it
Some ways exist to avoid it. In many printers if you simply print in black and white it will not print it. Even doing that some printers may still print a code. Simply using a shared printer may work. However, if the organization that owns the printer tracks that it may not be enough.
This method is old and they may be able to do it in other ways. Many newer printers store documents in a built in hard drive.
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