Spying on Keyboard Presses with a Software Defined Radio

Last year Milos Prvulovic, a computer science researcher uploaded some videos to YouTube showing how he was able to remotely and covertly record the keystrokes of a target laptop in another room wirelessly using just a software defined radio, magnetic loop antenna and some custom software.

The target laptop was first modified with special drivers that cause increased and unique memory and processor activity for each key that is pressed. As computers emit unintentional RF emissions, the modified memory and processor activity causes the target laptop to emit a unique RF signature for each key pressed. Milos used this fact to create a program that can detect the RF emissions from the target laptop, and show the key presses made from the target laptop on the spying PC.