[Cryptography] Generate Random Data From Sound Card

[Sampo Syreeni]

On 2026-03-06, David Kane-Parry via cryptography wrote:

>>> Try one command to convert the sound card into a TRNG.
>>>
>>> It should work with the audio muted.
>>
>> That's really cool! Same principle as the camera with a lens cap on. 
>> Ambient hiss is another source for free. Thanks for pointing that 
>> out, it's another arrow in the quiver of combating the Quantum 
>> Credulity Effect, that the very word "quantum" sucks people's brains 
>> out and leaves them incapable of thought.
>
> There's also, for example, the thermal noise that Intel uses as a part 
> of RDRAND.

Yes. You really don't even need to adjust anything, if there's some 
entropy in there at all. Just mix the signal into your entropy pool. 
Fortuna as an entropy pool algorithm probably has the best guarantees in 
this game, and the theoretical maximum goes by expander graphs, but 
really, anything having to do with broad symmetric cryptosystems is 
probably even quantum-secure in this application. Even if not probably 
secure right now.

If you think your PRNG is not secure, just cough into your microphone. 
Mix the capture in. The resulting turbulence will give you *lots* of 
physically random bits, probably on the order of 10kb per cough, and 
more if phlegmatic, as mine now is.

(I'm recovering from a weeks long viral lung infection, as a smoker, 
watching Stargate SG-1. Still just love the Asgård.)
-- 
Sampo Syreeni, aka decoy - decoy at iki.fi, http://decoy.iki.fi/front
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