[Cryptography] real random numbers

Watson Ladd watsonbladd at gmail.com
Sun Sep 15 10:48:13 EDT 2013


On Sat, Sep 14, 2013 at 12:29 PM, John Denker <jsd at av8n.com> wrote:
>
> This discussion will progress more smoothly and more rapidly
> if we clarify some of the concepts and terminology.
[...]
>
> Things like clock skew are usually nothing but squish ... not
> reliably predictable, but also not reliably unpredictable.
>
> I'm not interested in squish, and I'm not interested in speculation
> about things that "might" be random.  I'm interested in things that
> /guarantee/ a usable amount of entropy.  The second law of thermodynamics
> provides such a guarantee.

Clock skew is very well understood. In particular, I've thought about
using the DC-to-DC converter's oscillator in the power supply to
trigger interrupts, and use the usual timing based thing. The timing
is influenced by the amount of voltage that is on the
grid at a particular time, component variations, and thermal noise.
Phase noise is real!

More importantly, this provides a continuous stream of about 300k
deskewed random bits per second,
available as long as power is around.

Sincerely,
Watson Ladd


More information about the cryptography mailing list