New discovery to tackle forgeries

By Dan Simmons Reporter, BBC Click Online

The detection of forgeries is set to become a whole lot easier, thanks to a new technique involving inspecting the surfaces of objects microscopically.

Various techniques have been used over the years to address forgery

Faking things can be a lucrative business. False British passports can fetch up to £5,000 on the streets, and in 2003 more than half a million fake euro banknotes were seized in the EU.

Every so often, banks reissue notes with updated security features such as metallic strips, special inks, watermarks, or holograms.

In recent years attention has turned to incorporating chips or close-range readable tags in goods or ID cards. But tagging can be expensive.

Now, rather than by adding anything, researchers at London's Imperial College have discovered a way to identify almost any object by looking at it - very closely.

At a microscopic level the surface of my credit card looks very different from the surface of yours.

For decades scientists have been looking for a way to read these unique surface signatures reliably.

Now, Laser Surface Authentication (LSA) appears to do just that.

'Extremely excited'

A low intensity laser, like those used to scan barcodes in shops, is aimed at the object's surface. The scattered light rebounding back is captured by four readers.

We're doing things that have never been done before, and as a result we're getting levels of security and protection that people have only dreamed of before Professor Russell Cowburn, LSA inventor

It is this scatter pattern, caused by the various microscopic textures of the surface, which provides a reliable, readable signature, according to its inventor, Professor Russell Cowburn, from Imperial College.

"I'm personally extremely excited about this technology, because it's a completely new way of securing items, credit cards, ID cards, passports.

"We're doing things that have never been done before, and as a result we're getting levels of security and protection that people have only dreamed of before."

Unique fingerprint

Take three sheets of ordinary white paper. Manufactured in exactly the same way, they appear identical to the human eye.

The surface of one item will look very different from that of another

Once each sheet is scanned into the database its unique light speckle will reveal which sheet of paper it is.

When we tested a clean piece of paper, the probability of another sheet matching ours was estimated at 1 in 10 to the power of 120. That is a 1 with 120 noughts after it, which is more than the estimated number of atoms in the universe.

In practical terms, that is considered unique.

It works on plastic and many other surfaces too. And, importantly, nanotechnology has not come far enough for this unique fingerprint to be copied.

Professor Ross Anderson, from Cambridge University, says: "If you compare it, for example, with banknote printing, if I want to forge a £20 note all I have to do is replicate the manufacturing process that the Bank of England uses.

"But in order to forge a piece of paper with a known fingerprint I would have to invent a completely new manufacturing process, and I don't know how to do that."

Rigorous test

Working on pristine pieces of paper in a lab environment is all very well, but how would this technology cope with the rigors of real-world wear and tear?

We decided to test it out. First we screwed up one of three pieces of paper that we had scanned into the database. Would the now crumpled fibre structure make a difference?

No. Although the certainty of positive identification had dropped, it was still more than good enough for the ID industry.

The scatter pattern caused by the laser reveals a unique signature

What about scribbling on the surface? We often see banknotes with sums written on them, so could a little ink fool the reader?

No. In fact this time the reader identified the paper with more certainty because we placed it more precisely within the metal frame of the scanner, something that will be crucial when this technology is used for real.

To prove a point we tried to disrupt the surface with a metallic scouring pad, but the reader positively identified the correct sheet.

So it was time to break for coffee. How many times have we accidentally split a drink over an important document? This was the first time all four spoiling tests had been tried on one piece of paper.

Remarkably, its unique surface signature remained recognisable, and to an accuracy level considered acceptable by the security industry.

Processing for the huge databases that would be needed for many of the possible applications will need to be efficient enough to make the system useable. And for ID purposes, existing forms of establishing who should be carrying the ID - like a photo - will still be needed.

But this technology can effectively prevent duplication or counterfeiting.

With nothing needed to be added, it is a relatively cheap, new way of spotting the real thing, simply by taking a closer look.

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