[42829] in Cypherpunks
Re: Sources of randomness
daemon@ATHENA.MIT.EDU (Peter Monta)
Fri Nov 3 18:41:21 1995
To: cypherpunks@toad.com
Date: Fri, 03 Nov 1995 15:24:46 -0800
From: Peter Monta <pmonta@qualcomm.com>
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.
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.
Small biases/interferences that come from nonideally sampling such
voltages do not matter, since the entropy is still 1-epsilon bits per
sample (more for nonbinary samples). There is no "chink in the
armor" available for cryptanalysis---the user need only acquire
N*(1+epsilon) random bits rather than N bits.
The video-snow-noise described by Tim May is mostly Johnson noise
in the low-noise-amplifier electonics, not atmospheric or ionospheric
noise, at least above 50 MHz or so.
Cheers,
Peter Monta pmonta@qualcomm.com
Qualcomm, Inc./Globalstar
