[42832] in Cypherpunks
Re: Sources of randomness
daemon@ATHENA.MIT.EDU (Perry E. Metzger)
Fri Nov 3 20:01:13 1995
To: Peter Monta <pmonta@qualcomm.com>
Cc: cypherpunks@toad.com
In-Reply-To: Your message of "Fri, 03 Nov 1995 15:24:46 PST."
<199511032324.PAA22269@mage.qualcomm.com>
Reply-To: perry@piermont.com
Date: Fri, 03 Nov 1995 19:44:25 -0500
From: "Perry E. Metzger" <perry@piermont.com>
Peter Monta writes:
> I'm puzzled by the implication that thermal noise or avalanche or Zener
> noise is somehow inferior to noise from radioactive sources. It's not.
I didn't contend that its inferior. I contended that its difficult to
distinguish from sources of electronic interference and is easy to get
wrong.
> Take as an example Johnson noise, the voltage noise from a
> resistance. It's the result of the interaction of vast numbers
> of electrons. It is unpredictable in the same way that individual
> radioactive decay events are unpredictable, and they are both
> results of friendly quantum mechanics.
However, its very easy to be sure that the event in a radiation
detector was a radioactive decay event. It takes expertise to make
sure that the noise you hear off a noisy circuit isn't just
interference from other parts of the machine feeding back into the
circuit. The reason I like radioactive sources is that they are simple
and unambiguous in this way.
Someone can gimmick a zener diode or get it "wrong" a lot more easily
than they can get a radation event wrong.
Perry
