All you have to do is place your phone next to your keyboard to provide a direct channel for anyone to read what you are typing – and it’s all down to the vibration of the keys.
We all do it – place our phones down on the desk next to the keyboard. This might not be such a good idea if you want to keep your work to yourself.
A team of researchers from MIT and the Georgia Institute of Technology have provided proof of concept for logging keystrokes using nothing but the sensors inside a smartphone – an iPhone 4 to be precise.
The first interesting finding is that the accelerometer inside an iPhone 3GS wasn’t good enough to pick up the vibrations of the keys but the iPhone 4 produced a clear signal. This demonstrates not only that sensors are getting better, but the improvement makes a real difference.
The iPhone 4 was placed a few inches away from a keyboard and the keys were pressed while a sensor data was fed to two neural networks. The data was processed to produce a feature vector based on a range of temporal and frequency information. One network was trained to recognize the horizontal position of the key and the other the vertical position. The scan rate was on the low side, 100Hz, due to the limitations fo the hardware.