Bank customers could soon enter their PIN codes at cash machines just by looking at the numbers in the right order.
The system is designed to beat fraudsters looking over your shoulder to see which keys you press.
The technology, called EyePassword, is being developed in America – and High Street banks in Britain are already interested in using it.
It works by shining an infrared light on your eye. This stays in the same spot on your eye no matter where you look.
As you gaze at the cash dispenser key pad, your pupil moves. When your eye comes to rest on a number, a camera compares the position of your pupil with the fixed light in your eye.
The system is then able to work out which direction your pupil has moved in and how far and, therefore, which number you are looking at.
EyePassword has a three per cent error rate and it can take six times longer to enter your pin.
But Lloyds, Barclays and Royal Bank of Scotland have expressed an interest in the technology.
However, its inventor, Manu Kumar, of California’s Stanford University, warned: “There are lots of issues to be resolved, probably the biggest one being cost.”
Computer security specialist Dr Jeff Yan, of Newcastle University, said cash dispensers using EyePassword could cost £5,000, £3,000 more than a conventional ATM.