hardware RNG

[Bill Stewart]

At 11:14 AM 9/10/2013, The Doctor wrote:
>By default, the firmware running in the on-board microcontroller
>records the time between three successive hits on the 'tube (t1, t2,
>t3).  If (t2 - t1) < (t3 - t2), it prints a 0 to the serial port,
>else, it prints a 1 to the serial port.  Hardly high resolution
>entropy, but it can be stirred into an entropy pool.

I don't know how many bits/second you're getting out of it,
but it's definitely high quality entropy, one real bit per bit,
assuming they don't reuse the intervals.
(It's ok to use t3 as the starting point for the next two intervals,
so      bit2 = ( (t4-t3) < (t5-t4) ),
but not bit2 = ( (t3-t2) < (t4-t3) ), which would be correlated with bit1.)