Smartphone Keystroke Logging Using the Motion Sensor
“When the user types on the soft keyboard on her smartphone (especially when she holds her phone by hand rather than placing it on a fixed surface), the phone vibrates. We discover that keystroke vibration on touch screens are highly correlated to the keys being typed.”
Applications like TouchLogger could be significant because they bypass protections built into both Android and Apple’s competing iOS that prevent a program from reading keystrokes unless it’s active and receives focus from the screen. It was designed to work on an HTC Evo 4G smartphone. It had an accuracy rate of more than 70 percent of the input typed into the number-only soft keyboard of the device. The app worked by using the phone’s accelerometer to gauge the motion of the device each time a soft key was pressed.