[5349] in cryptography@c2.net mail archive
Re: linux-ipsec: /dev/random
daemon@ATHENA.MIT.EDU (John Denker)
Wed Aug 4 13:58:44 1999
Date: Wed, 04 Aug 1999 11:03:34 -0400
To: hugh@mimosa.com
From: John Denker <jsd@research.att.com>
Cc: Paul Koning <pkoning@xedia.com>, cryptography@c2.net,
linux-ipsec@clinet.fi
In-Reply-To: <Pine.LNX.4.10.9908040946190.9824-100000@redshift.mimosa.co
m>
At 10:08 AM 8/4/99 -0400, D. Hugh Redelmeier wrote:
>
>I think that this description reflects an inappropriate understanding
>of entropy. Entropy is in some sense spread throughout the whole
>output of /dev/urandom. You don't use entropy up, you spread it over
>more and more bytes of output. This view, of course, depends on
>trusting the hashing/mixing to do what it is supposed to do.
What matters here is not your understanding or my understanding of what
entropy is. What matters to me is /dev/random's opinion of how much
entropy it has on hand. Reads from /dev/urandom deplete this quantity,
byte for byte, so that heavy demands on /dev/urandom cause blockage of any
processes that make any use of /dev/random. I renew my assertion that this
constitutes, shall we say, an opportunity for improvement.
