Confessions of a Keytarist

According to an article on the BBC tech news website, it is possible to determine individual pc keystrokes by monitoring power fluctuations in your mains supply.

According to the article, the six wires that make up PS2 cables are usually very tightly packed together and poorly shielded, leading to “leaking” of  information from the data wire, onto the ground wire.
The current on this ground wire eventually flows, via the motherboard and then the PSU, makes it way through the power cable and out into your mains ring.

Because the clock speed of keyboards is much lower than anything else used within a PC, it’s relatively easy to then filter out the other “background noises” also flowing along the ground circuit, until you’re left with just the key presses, which can the be easily read on an oscilloscope.
Then, because the data is sent one bit at a time, it’s simply a case of joining the bits and calculating back to the original key.

Whilst this is quite cool, the pair who have been researching this type of “snooping” have so far only proved it works up to a distance of 15 metres, and also requires the keyboard to be PS2, I think the discovery has come a little too late…

Original article: BBC News – Technology