US scientists have developed a software algorithm that creates a physical key based solely on a picture, regardless of angle or distance.

The project, called Sneakey, was developed to warn people about the dangers of haphazardly placing keys in the open or posting images of them online.

"People will post pictures with their credit cards but with the name and number greyed out," says Professor Stefan Savage of University of California, San Diego (UCSD), who helped develop the software. "They should have the same sensitivity with their keys."

When Savage and his students searched online photo sharing websites, such as Flickr, they found thousands of photos of keys with enough definition to replicate.

The software could also use an image captured by a mobile phone camera to snap a quick picture of stray keys on a table top.