Saturday, 18 May 2013

"Unintended payments" with contactless payment cards - a problem with an 1836 solution?

Contactless credit and debit cards are normal chip payment cards with an embedded antenna, or aerial. They work with a card reader only and have a maximum intended range of 5cm. However, there have been reports of unintended payments by cards that are 30cm. away from the nearest card reader. When payment is requested, a card reader sends out a radio frequency signal to which the card responds.

There is a transaction limit of £15, above which the card holder's PIN will be requested. As a further security measure, the familiar chip and PIN feature comes into play after a certain number of contactless transactions. Depending upon how high that number is set by the banks, various amounts could be taken from the holder's account without their knowledge, as they would only have to have their card close to a reader for the transaction to be effective.

It doesn't take a great leap of imagination to see how technology-savvy criminals could capitalize on the "below-threshold no-PIN" feature of the system. They are already known to collect account-compromising information by using dummy cash machines, covert card readers, and spy technology on real cash machines. How long before we see, or rather don't see, pocket covert card readers being used by criminals mingling within crowds?

The Luddite response to the threat might be to attempt to thwart progress and refuse to carry contactless cards at all. However, scientist Michael Faraday, born in 1791, invented a device which shielded its contents from electro-magnetic radiation. Static electricity and radio signals are examples of electro-magnetic radiation, and the device invented in 1836 is called the Faraday cage.

So the question becomes "how can we make a Faraday cage to protect our credit and debit cards"? After all, such devices are often built as whole rooms to contain sensitive equipment. The answer is actually very simple: a metal biscuit tin is a Faraday cage; a wrap of tin or aluminium foil is a Faraday cage; the anti-static plastic film that protects new electronic equipment is a Faraday cage.

We just need to make sure that our cards are surrounded by a piece of conductive foil or film. Crafters of card holders and wallets can easily incorporate this in their designs. Ready for the cashless society?

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