[Cryptography] cheap sources of entropy

[Bill Frantz]

On 1/18/14 at 12:17 AM, iang at iang.org (ianG) wrote:

>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 think what is happening here is the effective ISO is being 
pushed up by the low light so there is a lot of noise in the 
amplifiers used to read out the sensor cells. What you are using 
is thermal noise in the amplifiers. You get a lot of readings in 
one photo, and it should be a good source.


>Open question:  What do people think of the production of big important
>keys using the old compliance method of "must use a HSM" now ?

I have always looked at HSMs as black boxes built by people I 
don't trust. If I built it I would feel different, but you 
should be uncomfortable using my HSM. Getting mutually 
suspicious people to trust the same HSM is an interesting 
social/technical problem.

Cheers - Bill

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