Forget about using a pen to sign a credit card slip, or even tapping in a secret number. In the future, you could authorise payments by simply moving your finger over your flexible friend.
A leading professor at the Massachusetts Institute of Technology has suggested using radio tags in credit cards as a kind of virtual signature. Professor Ted Selker said the way someone moved their finger over the card would alter the radio transmission, producing a signal unique to that person.
"I could have some gesture and that would be my signature," he said, "it would be like a personal handshake."
The idea of putting radio tags in credit cards is not as far-fetched as it sounds. Mastercard has been experimenting with the technology, known as Radio Frequency Identification (RFID).