A nanotechnology experiment that went wrong could lead to the ultimate weapon in the fight against the forgers

Professor Russell Cowburn normally views small things through a powerful electron microscope. But as professor of nanotechnology at Imperial College London, he's come up with a big idea for winning the war against counterfeits. No matter how clever security technologies such as holograms, metal strips or special inks become, criminals soon bypass them.

"There is an arms race. People introduce new technologies and somewhere between six weeks and six months later, they've been cracked," says Cowburn.

Laser surface authentication is now joining the battle and, if Cowburn's dream comes true, may be the ultimate weapon for the security marking industry.

The idea relies on a problem in nano-technology: it's very hard to make exactly the same thing twice at the nano scale. He was originally using microchips and scanning their unique patterns with a laser when an experiment went wrong.

"One day the chip fell off the paper backing that it was being tested on and the laser just hit the paper instead. Whereas we would have expected to have got no signal, we actually got a signal that had all of the right characteristics for a security device. That was enormously surprising," says Cowburn.

Rather than reaching for the glue, Cowburn investigated further and found that ordinary paper gave robust security signatures. The random pattern of the paper fibres scattered back the laser beam to detectors, giving far better results than the microchip.

After tuning the laser system, he also discovered that the probability of two pieces of paper producing an identical reading was unimaginably remote.

Credit cards, metals and coated paper boards were swiftly tried with the same startling results. Putting the now defunct microchips aside, Cowburn realised that all he needed was to scan an item's surface, convert the reflected laser speckle pattern into numbers, and store a security signature in a database.

Portable laser scanners would then sort the fake from the genuine or help with track and trace. Cowburn has set up Ingenia Technology Ltd to exploit the newly patented device and is involved in a secret trial with an overseas organisation. The company also recently won an award as the world's most promising security technology startup business. "With our technology, everything carries its own fingerprint. We can very easily take the item and scan it," says Cowburn.

Ross Anderson, professor of security engineering at the University of Cambridge's Computer Laboratory, recalls the pioneering Shakespeare hologram on cheque guarantee cards in 1988 which was later reproduced by forgers in China - he even bought one in a Singapore market. Laser surface authentication, he reckons, will stump even the most resourceful forger.

"The interesting thing is that you're actually looking at naturally occurring randomness. I don't know of any process that can be used to forge this," says Anderson.

The problem for the forger is this. Magnify a piece of paper only 100 times and you'll see the crisscrossing fibres that make up its complex irregular surface. And that's just the beginning, as the scanner that is used to read the security signature can detect surface irregularities of less than a few hundred nanometres in size - a nanometre is one millionth of a millimetre.

To create an identical security signature for a document, box or credit card, the forger would have to duplicate the surface including all the imperfections at the nano-scale. As these were created randomly during the original manufacturing process, the forger has no chance of success - security is built in from the day the item was made.

"The advantage of the technology is that you don't have to do anything special to your materials - in many applications that's a killer advantage," says Anderson. He thinks the technique is useful for luxury goods, safety-critical items like car parts, and on grey-market products.

Anderson also mentions the nuclear industry where uranium container seals have to be tamper-proof and all waste carefully tracked.

And, more controversially, he says that laser surface authentication might provide rapid checking of ordinary paper passports without the need for costly microchipped identity cards.

Thanks to a failed experiment, Professor Cowburn's new weapon may win the anti-counterfeiting war.

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