There is a famous scene in the 1983 film, Blade Runner where the protagonist verifies the manufacturer of some artificial snake scales. They turn out to be the work of IBM, a fact imprinted in open text on each scale so invisibly that only a scanning electron microscope can read the letters.

Life mirrors fiction more. Some months ago, it was discovered that colour laser printers from manufacturers such as Canon and Xerox were adding special dots to prints apparently as identifiers. What was going on?

Now researchers at the Electronic Frontier Foundation (EFF) have discovered that the manufacturers put them there as part of a special deal with the U.S. authorities, worried about counterfeiting. The dots tell them a printer’s serial number, and the time and date of a particular print.

They’re deciphered the codes for only one printer, the Xerox Docucolor, using a microscope and some blue light, but other are believed to follow similar a similar design.

Now that the cover has been blown on the scheme, forgers have to find a way of forging or disrupting the dots, assuming they don’t want to leave an information trail.

As the coded dots will be on every document printed by the affected machines, this has prompted the EFF to ask some obvious civil liberties questions.

Even those of us placid enough not to troubled by such issues should reflect on the way the digital takeover of information is sending out tentacles into the physical world. It’s not Blade Runner because it’s actually more profound. It is not just telling us where something was made, but potentially where and when it was thought.