The tempest effect

[Scarlets]

I have been told of a method the military use to intercept messages emitted from PC's

They can basically track whatever is on the monitor by using what has been called The Tempest Effect. I think its because every machine radiates electromagnetic energy that can be broken down to form the image on the monitor elsewhere.

Has anybody heard of this and can anybody tell me more?

[fo3nix]

yea it's true. only works for a short range though, as a too great distance would add too much electromagnetic interference. so if you see a strange florists van parked outside your house with a strange arial be worried! ;-)

this is why certain security programs like PGP will hide your passphrase as you type (well, one reason. the other is that some tools can sometimes discover a password that's been converted to ***'s on the screen).