[Cryptography] Generate Random Data From Sound Card

[Byrl Raze Buckbriar]

On Thu, 5 Mar 2026 09:53:22 -0500
"Theodore Tso" <tytso at mit.edu> wrote:

> The better camera do capture the output of the senor when the shutter
> close to try to reduce noise from high ISO shots --- but the fact that
> this *does* work means that it's not true quantuum noise.  If there
> are characteristics sensor quirks that are there between successive
> sensor grabs, then you can't really use this as unpredictable
> randomness for cryptographic purposes.  Fortunately there is *some*
> quantuum noise, but that's not why dark-frame substraction works.

Because of the complexity of the circuitry and algorithms involved, I don't have the time or expertise to analyze the camera/video devices and data or ballpark what would be a safe data to compression ratio. So I haven't done anything really serious with it, other than tinkering and using it to add some data to my testing entropy pools.

I like the audio card noise because it appears to be constant electronic hiss and is much easier for me to use with a reasonable assumption of [mostly] true unpredictability. I have dumped some files of a few hundred megs and pruned the predictable bytes and hashed as lines to a manifest. I have yet to see a duplicate hash after grinding out hashes for extended time.

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