There is a paper from one of the guys who made RSA about that.
They can reconstitute private keys, by listening repeatedly to the sound the power supply of a laptop makes when encrypting/decrypting emails, from 5m away.
the good old days in the military where our main communications computers and such were in shielded areas to prevent leakage outside which could be picked up.
They can reconstitute private keys, by listening repeatedly to the sound the power supply of a laptop makes when encrypting/decrypting emails, from 5m away.