26 March 2014

Nanowire ‘impossible to replicate’ fingerprints could eliminate fraud, counterfeit goods

nanowire fingerprints
We’ve written a lot about how nanowires might be used in future, Moore’s law-defying computer chips but now a research group in South Korea thinks they have another, more immediate application: Counterfeit prevention. By randomly dumping (their words, not mine) multicolored nanowires onto a plastic film, the researchers say they have created patterns (a nanowire fingerprint if you will) that are nearly impossible to replicate. These fingerprints (which are much smaller than the eye can see) could be embedded in electronics, money, drugs, and so on, to prevent fraud and the proliferation of counterfeit goods.

To create the patterns, researchers at Korea Advanced Institute of Science and Technology (KAIST) start with simple silver nanowires. They then coated the nanowires in a silica shell, which was then reacted with one of two fluorescent dyes (red and green). A mixture of the nanowires, in solution, are then simply dropped onto a piece of plastic. One microliter (a thousandth of a milliliter) is enough to create five or six nanowire fingerprints, each containing a few dozen nanowires.
How to make a random nanowire pattern
How to make a random nanowire pattern

The dropping process (presumably via a pipette) introduces what the researchers call natural randomness. Basically, due to tiny fluctuations in air pressure, gravity, etc., the nanowires always land on the plastic film in a different pattern. With just 10 or 20 nanowires distributed randomly throughout an area, bent and folded over each other, and with the added complexity of two different colors, it is essentially impossible for any two patterns to be the same.

Suffice it to say, but these nanowires which are about 70 nanometers across are invisible to the naked eye. The patterns only appear when viewed under an optical fluorescence microscope. These patterns would be stored in some kind of database, and then attached to the object that needs to be protected against fraud a credit card, money, drugs, designer purses, etc. There are some other techniques (digitization, barcoding) that would reduce the amount of storage space required by the database, and remove the requirement to have a fluorescence microscope handy.

What I love about this approach is that, on the one hand, it’s incredibly secure but on the other hand, it’s dumbly insecure. The only reason that these random fingerprints are secure is because the nanowires are too small to be easily manipulated; it would take an untenable amount of time to recreate one of the patterns by manually moving the nanowires around with some tiny tweezers. It’s a bit like taking a very long piece of rope, tying a trillion random knots into it, and calling it secure. Yes, it’s kind of secure, but only because no one wants to spend the time trying to undo the knots. Still, if we’re being fair, you could say the same about cryptography, too and it doesn’t take away from the fact that, right now, these random nanowire patterns are very secure indeed.



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