Can you trust your printer? Will your photocopier defy you? The answer is ?yes,? but only under odd conditions that would never affect the vast majority of users. Since printers are admittedly a dry subject for people who (unlike us) aren't dedicating their time to making them work, we thought we'd spice things up with weird facts.
Your color laser printer is a spy!
It's true: Every sheet your printer spits out includes the date and time it was printed, and the serial number of the printer it was on ? but you'll probably never notice it. All of this information is encoded on yellow dots a tenth of a millimeter across. Someone who knows where to look, how it's encoded and has a microscope on hand can track every page you produce.
Why? The answer isn't entirely clear, but it seems that the US Secret Service may have requested this against the threat of printers producing high quality counterfeit currency. These secret yellow dots appear on printouts from majority of commercially available color laser printers.
Groups like the Electronic Frontier Foundation would like to know exactly who knows what these codes mean, and how law enforcement agencies use them. Take a look at the mystery dots yourself, at the Wikipedia article on Printer Steganography.
In fact, you don't have a license to print money.
On a related note, many modern photocopiers have refused to copy currency since about the mid-90s. Photocopiers are pretty smart now, but even they need help to detect paper money. Once again, governments and corporations quietly cooperated.
As a result, many copiers are designed to detect and reject any paper with a special pattern made of five circles ? and most banknotes feature that pattern hidden in the bills. Independent researchers call the pattern the ?EURion Constellation? (it looks like the Orion constellation, and you find it on Euro notes), but its real name and exact specifications are secrets known only to the anti-counterfeiting community.
This stuff sounds strange, but it's true ? and above all, it's a testament to how sophisticated modern printer, toner and copier technology is.
