Think twice before you start printing your own currency

Your colour laser printer or photocopier may be printing a hidden ‘bar code’ on every document.

I must confess that I thought this to be an urban myth, or something dreamt up in a Tom Clancy novel, but clearly I was wrong: many colour laser printers and photocopiers print a hidden ‘bar code’ of dots within the document so that the serial number of the printing unit can be identified by law enforcement authorities. This watermark normally consists of a number of displaced yellow dots within the document, although there are other alleged techniques out in the wild. Printed documents can be tracked back to an individual printer, allowing the FBI and others to identify counterfeiters, moles, ransomers and anyone else using high-end printers for nefarious purposes.

Aside from the inevitable privacy concerns that arise here, what really disturbs me is that this suggests that the FBI and a large number of technology manufacturers have successfully implemented a common framework for monitoring a huge number of devices. If they’ve embedded hidden watermarking here, where else does it exist?

All of which means I have a spare batch of €500 notes that are suddenly of little use to me. Any takers?