[Cryptography] cheap sources of entropy

[Jon Callas]

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> Jon Callas (I think) a long time ago suggested pointing your cheapo USB
> camera at a photographer's grey card in low light.  The theory is that
> the cells in a camera seek for information and if they don't see
> something that is worth reporting, it drives them a little tipsy.  The
> claim is that this effect can drive them into some form of quantum
> uncertainty.

I was more blunt -- leave the lens cap on, even. There is quantum noise in the sensor, and if you take a frame and hash it, it almost certainly has more true randomness than the width of your hash function.

If you are in doubt, take two pictures and hash them. Or whatever makes you comfy.

	Jon


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