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Comment by JulianMorrison | Hacker News Reader

Simple general extrapolation: if your device contains any software actuated part whose emissions of any form can be detected via passive sensing, or whose operation can be detected via active sensing, then the device cannot be air gapped.

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Simpler general extrapolation - every (macroscopic[0]) physical process radiates information about itself at the speed of light. The information is always "out there", there's no "airgapping" that. The question is, and always was, how expensive and difficult is it to read that information.

[0] - not sure about some quantum ones, but then again, those that do not radiate information aren't exactly very useful

Can't you just use a faraday cage, sound matting, and add some filters on the mains power coming into the power supply and any USB/monitor cables coming out to decouple any potential crosstalk? This is a solved problem in very sensitive equipment like electron microscopes, where the smallest signal or vibration can leak (from a USB keyboard or another machine on the same power line on the other side of the building, for example) and effect the electron beam.

The other alternative would be to raise the electrical and auditory noise floor to the point where the leaked signals get lost in random noise. Then you'd have to perfectly synchronize the external sensors with the internal clocks to be able to extract any useful information.

Obviously these solutions aren't perfect (what is?) but short of placing a spatially filtered passive radar in the same room, you wouldn't get any usable information leakage.

You're still just raising costs, not making it impossible. Which is fine, because security is always about raising costs to make break-ins not worth the while.

Clive Robinson on Schneier's blog came up with a thorough notion years ago: energy leaks plus "energy gapping" systems. He said if any form of energy or matter could transfer from one system toward anothet device then it should be considered a potential leak. So, you have to physically isolate them then block the whole spectrum practically.

Each new story supports his model. Energy gapping for the win.

In other words, it's roughly as hard as keeping a quantum qbit from decohering, and for the same reason.

Not so trivial, then.

Haha. I won't go that far. You just shield from as many forms of sounds, light, EM, etc as you can. Alternatively, build memory and info-flow security into your hardware, do POLA at device level, and use TEMPEST-style hardware. Also, as in EMSEC tents or safes, one can separate security levels into their own shielded cages/racks. Already products for that although not sure if energy gapping is thorough enough.

Yeah, you could probably modulate some CPU load and emit noise from the capacitors that are sitting on the power stage of the CPU.

Scary stuff...

https://www.tau.ac.il/~tromer/acoustic/

there was an article on HN recently about using chemical reactions to do some of the computer processing, with the net benefit that the random nature of the reactions would mask these emitted signals.

edit: the company is http://chaologix.com/

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