
Lamphone: Real-Time Passive Sound Recovery from Light Bulb Vibrations - sohkamyung
https://www.nassiben.com/lamphone
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lsb
The graphs they present show the largest response with 110db audio, which is
about as loud as a car honking right in front of you[1], but even still, to
eavesdrop on corner offices from tens of meters away with nothing but a
telescope and a video recorder is a huge feat.

[1]
[https://www.chem.purdue.edu/chemsafety/Training/PPETrain/dbl...](https://www.chem.purdue.edu/chemsafety/Training/PPETrain/dblevels.htm)

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madengr
Pointing a telescope at tens of meters away will get you noticed pretty quick.
Now one can sell lightbulbs with noise modulation to defeat it.

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hedora
Yeah, not sure why they patented the attack, and not the defense.

It seems much easier to enforce a patent against technologies that defeat the
attack.

From the article, it looks like one can build the surveillance device from a
few readily available parts, and then hack together the signal processing
software. That’s not even in violation of the patent if you don’t sell /
distribute it.

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goodmachine
HN has a real weakness for cool surveillance technology.

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TeMPOraL
Sure. I for one have a huge weakness for this kind of tech, because it's an
archetypal hack - a clever trick to pull something out of a system, whether
the system likes it or not.

It's also interesting because it's deeply grounded in reality. It's no gluing
crappy APIs together to solve a "problem" twenty layers deep in someone's
convoluted business shenanigans. It's using reflected light to learn about
mechanical vibrations at a distance, to show that the information _is_ there,
despite what you'd hear from people who don't comprehend how reality works.
It's a nice reminder that everything that happens interacts with everything
around it, and information about it spreads out at the speed of light. Most
side channel attack are like this, which is why I find them interesting.

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anigbrowl
I have the impression (not least based on the original spectrograms) that the
sound sources were quite loud and would have been annoyingly loud in the room,
so your whispered conversations are probably safe for a while yet. But it's
very impressive work nevertheless. I look forward to trying it out.

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082349872349872
So what's the gold standard of whispered convos these days? Last I'd been
paying attention it was standing in the surf.

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dTal
I believe what you do is you record an hour of normal conversation and then
play back dozens of timeshifted copies simultaneously. Any system is going to
have a very hard time filtering out noise with the same statistical properties
as the signal - including you. You might have to stand quite close together...

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nitrogen
If I'm remembering the right book, I believe something like this was described
in Anathem by Neal Stephenson (not crucial to major plot).

