The method exploits a feature meant to aid typing on small touchscreens: magnified keys. iSpy can identify text typed on a touchscreen from video footage of the screen or even its reflection in windows or sunglasses. Video from an ordinary mobile phone camera can be used to spy on a person from 3 metres away. And a snoop with a digital SLR camera that shoots HD video could read a screen up to 60 metres away.
"We were surprised at how well [this idea] worked."
Bonus points for the fact that one of the researchers is a former Hopkins professor and for a quote from a current Hopkins professor.