The software can reveal what others are texting in their personal emails or text messages sent forth on their smartphones just by the snooper using a smartphone camera or advanced camera like a digital SLR that shoots HD video, which could read a screen up to 60 metres away.

The UNC research team, Rahul Raguram, Andrew White, Dibenyendu Goswami, Fabian Monrose and Jan-Michael Frahm, discovered they could be on the second floor of a building and read a phone on the ground, leave alone sitting on a bus and catching all the text of a nearby passenger. How much text at how far a distance depends on the spy device used, whether it is a regular smartphone camera or more advanced camera with lenses.

The team report their findings in the paper, “iSpy: Automatic Reconstruction of Typed Input From Compromising Reflections” and presented their work at the Conference on Computer and Communications Security (CCS) in Chicago.

One of the nice features in smartphones, designed to help users type on small touchscreens, is magnified keys. Letters on the virtual keyboard rise up in bubbles. That is also one of the features that made it so easy for the snoopers to view footage and identify the letters based on the bubble locations. The program correctly identified letters over 90 percent of the time. Obviously, the UNC team did not do their research in order to promote a mass rush for technology that can spy on what people are saying on their mobile devices.

Their aim is to call attention to the fact that with the freedom of mobile technologies comes the burden of adjusting to the digital life, where special privacy measures may be needed.