|WikiProject Cryptography / Computer science||(Rated Start-class, Low-importance)|
While the research of Dmitri Asonov and Rakesh Agrawal is very intresting, it's not really cryptoanalysis but more keylogging, so I don't think that they should be mentioned here as the first thing. The more intresting research is the research from Adi Shamir and Eran Tromer, which is more side channel and cryptoanalysis in nature than the first imho. (edit: oops, this was me) --Soyweiser 10:38, 10 April 2007 (UTC)
Acoustic Emission = Microphonics
Hi, great article, up to date.
After noticing the acoustic emissions used for side-channel attack described as humming, I thought a little background on what's going on here (the physics) might help the article and readers. We've got components radiating at 38KHz when digital pulse trains go through, not 60 Hz line hum. How can this happen? The new paragraph:
Acoustic emissions occur in coils and capacitors because of small movements when a current surge passes through them. Capacitors in particular change diameter slightly as their many layers experience electrostatic attraction/repulsion or piezoelectric size change . A coil or capacitor which emits acoustic noise will, conversely, also be microphonic, and the high-end audio industry takes steps with coils  and capacitors  to reduce these microphonics (emissions) because they can muddy a hi-fi amplifier's sound.
Hope everyone likes it. I did not say that the Printed Circuit Board (PCB) on which the components may be mounted acts like a sounding board to amplify the emissions. Also, don't tell anyone, but the secret for stabilizing large polypropylene or mylar capacitors for high-end audio gear -- to kill either the emissions or the microphonics, whatever your game -- is to dip them into liquid nitrogen. The wrenching thermal contraction locks the layers against all movements driven by electrostatic forces. Too bad I have no reference -- this is lab lore, keep it to yourself. Finally, those piezo effects are mostly in ceramic capacitors, not the polypropylene/Mylar ones.