When last we wrote about the Electronic Frontier Foundation's attempts to decipher the hidden watermarks in color laser printers, the group had identified that some miniscule yellow tracking dots appeared under blue light.
Now the intrepid civil liberties group says it has cracked the tracking codes used in Xerox printers. (Other codes appear in printouts from machines by manufacturers such as Canon, Epson, HP, and Lexmark.)
While no law appears to require the manufacturers to embed the hidden dots -- which encode the printer's serial number and time and date information -- they nevertheless do it voluntarily as a way to help the Secret Service reduce counterfeiting.
In a Xerox DocuColor printout, for instance, a rectangular grid of 15 by 8 tracking dots are printed on every color page. Blue light and a magnifying glass makes them visible. EFF has even made source code of a Xerox decoding program available.
It's one thing to detect counterfeit dollar bills. But the hidden dots may erode Americans' right to anonymity by making it more difficult to print out political or religious pamphlets anonymously.
"It shows how the government and private industry make backroom deals to weaken our privacy by compromising everyday equipment like printers," said EFF Senior Staff Attorney Lee Tien. "The logical next question is: what other deals have been or are being made to ensure that our technology rats on us?"