Comment Articles

Leaving your prints all over the place

Rupert Goodwins ZDNet.co.uk

Published: 25 Feb 2004 16:40 GMT

Passwords are dying, says Bill Gates, and who are we to disagree? Horrible things: we have to use so many of them now, and people just aren't any good at remembering large sets of random words and regurgitating them correctly. His answer is to move to a tamper-resistant biometric ID card, where certain parts of yourself are digitised and printed out as a barcode: if you present that and the information on it doesn't correspond to your biological bits, either the card or the body isn't what it claims to be. Access denied. If everything's OK, in you go.

For some of us, this is already happening. If you enter the US on a visa -- as us reprobate hacks must -- you'll be electronically scanned for fingerprints and facial features, and the data stashed away on some enormous Department of Homeland Security Database. I got my dabs taken and my long-haul-bloated face snapped last week: for now that data just sits around, presumably waiting to go wrong at the point of maximum inconvenience. But it's destined to be printed as a computer graphic in my next passport, ready to join other graphical information that's already out there sucking paper into the digital world.

Take the new US banknotes. Despite the country's unfathomable addiction to making all notes the same size and colour -- "Why on earth would you want it any other way?", asked one confused American -- the latest designs have a whole set of subtle shades and other security features to make them harder to forge. One of these is a selection of apparently random circles designed to trigger pattern recognition routines in copiers, scanners and image editing software.

The core pattern, which looks something like the constellation of Orion but with a single central blob instead of the three star belt, is also to be found on new notes the world over. You can find it on the UK Darwin tenner under the foliage on one side and in the central oval on the other, just to the left of Queenie. On the £20, it's disguised as notes on a musical stave -- Orionic, as the Irish might say, given the role of music in the debate on digital copy protection. See the pattern once, and there's a particularly good example on Cambridge cryptographer Markus Kuhn's website, and you'll start spotting it on every banknote you handle.

Finding this pattern is sufficiently easy that a wide range of software can spot it and make an appropriate response. Anything that might be expected to handle a document image is fair game -- not only printers, scanners and photocopiers, but screen and printer drivers, digital-camera firmware, and even router and hard disk components could suddenly acquire a legally-mandated blind spot. Adobe's Photoshop has it already, although the company won't say how that came about, and we have no way of knowing what else is now primed to join the dots.