The Ecole Polytechnique team did its work over the air. Using an oscilloscope and an inexpensive wireless antenna, the team was able to pick up keystrokes from virtually any keyboard, including laptops. “We discovered four different ways to recover the keystroke of a keyboard,” said Matin Vuagnoux, a Ph.D. student at the university. With the keyboard’s cabling and nearby power wires acting as antennas for these electromagnetic signals, the researchers were able to read keystrokes with 95 percent accuracy over a distance of up to 20 meters (22 yards), in ideal conditions.

If pulling keystrokes out of thin air isn’t bad enough, another team has found a way to get the same kind of information out of a power socket. Using similar techniques, Inverse Path researchers Andrea Barisani and Daniele Bianco say they get accurate results, picking out keyboard signals from keyboard ground cables.