News Security keys leaked via touch, claim researchers

I really don't understand how this works or how it could possibly work.

How does measuring a ground connection tell you what's going on, other than, "It's On" or "It's Off", or "Heavy usage" or "Light usage"?

 

Kind of makes sense, the ground (in fact all terminals) will be noisy, that noise is caused by background interference. So it looks like interference emitted by the the logic part of the computer is interfering with the power circuitry then being leaked into the ground and contains useful information. While this interference is minuscule and negligible to power function it appears to be significant enough to be picked up and separated, an unfortunate side effect when you consider the two systems are isolated because conventionally one thinks isolation is most important so that the power circuitry does not interfere with the logic side since it is several orders of magnitude more powerful, this lot have looked at it the other way round, its ingenious really.

Thats why it would work on wireless frequencies emitted too. If you have the expertise and you know what you are looking for, you get a a very sensitive spectrograph and can filter off all the other noise, you reconstruct the useful data from any emission then apply cryptography to decrypt the information you need.

 

And here's where I see the downfall. If the PC was only processing crypto keys and wasn't running (for example) an OS, outputting any video/sound, listening for interrupts, and generally being a computer; this could be feasible.

IMHO

 

This is what's known as a Side Channel attack, specifically via power analysis. The novel part here is the connection via a squishy meatbag electrode rather than a metal clamp or probe.