hardware RNG

[Bill Stewart]

At 12:32 PM 9/9/2013, Juan Garofalo wrote:
>very naive question here :
>Wouldn't it be possible to build a RNG using something like a zener 
>diode and a $2 microcontroller?

Sure, and if you like playing with Arduinos and similar electronics, 
it'd be a good experiment.

The main issues you run into (besides getting a decent fast USB 
interface without having to use surface-mount electronics, which are 
annoying to solder),
are validating the quality of the randomness and getting enough speed 
to be useful (which depends not only on your noise quality but also 
on whether you're using a USB-enabled chip or just bit-banging.

DieHard http://en.wikipedia.org/wiki/Diehard_tests is probably still 
the standard quality test - your noise is almost certain to be 
biased, rather than purely uniform, so you'll need to whiten the data 
and adjust your entropy estimates appropriately.