Pickens writes: "BBC reports that researchers have created software that gives images an expiration date by tagging them with an encrypted key so that once this date has passed the key stops the images being viewed and copied. Professor Michael Backes, who led development of the X-Pire system, says development work began about 18 months ago as potentially risky patterns of activity on social networks, such as Facebook, showed a pressing need for such a system. "More and more people are publishing private data to the internet and it's clear that some things can go wrong if it stays there too long," says Backes. The X-Pire software creates encrypted copies of images and asks those uploading them to give each one an expiration date. Viewing these images requires the free X-Pire browser add-on. When the viewer encounters an encrypted image it sends off a request for a key to unlock it. This key will only be sent, and the image become viewable, if the expiration date has not been passed."