From owner-freebsd-security@FreeBSD.ORG  Thu Sep 18 18:36:37 2003
Return-Path: <owner-freebsd-security@FreeBSD.ORG>
Delivered-To: freebsd-security@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 2CCBA16A4B3
	for <freebsd-security@freebsd.org>;
	Thu, 18 Sep 2003 18:36:37 -0700 (PDT)
Received: from bas.flux.utah.edu (bas.flux.utah.edu [155.98.60.2])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 78A1443FDD
	for <freebsd-security@freebsd.org>;
	Thu, 18 Sep 2003 18:36:36 -0700 (PDT)
	(envelope-from danderse@flux.utah.edu)
Received: from bas.flux.utah.edu (localhost [127.0.0.1])
	by bas.flux.utah.edu (8.12.5/8.12.5) with ESMTP id h8J1aaR0023080;
	Thu, 18 Sep 2003 19:36:36 -0600 (MDT)
	(envelope-from danderse@bas.flux.utah.edu)
Received: (from danderse@localhost)
	by bas.flux.utah.edu (8.12.5/8.12.5/Submit) id h8J1aaWF023079;
	Thu, 18 Sep 2003 19:36:36 -0600 (MDT)
Date: Thu, 18 Sep 2003 19:36:36 -0600
From: "David G. Andersen" <danderse@cs.utah.edu>
To: "Devon H. O'Dell" <dodell@sitetronics.com>
Message-ID: <20030918193636.A94860@cs.utah.edu>
References: <3F6A5BBF.3020102@sitetronics.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.2.5.1i
In-Reply-To: <3F6A5BBF.3020102@sitetronics.com>;
	from dodell@sitetronics.com on Fri, Sep 19, 2003 at 03:28:31AM +0200
cc: freebsd-security@freebsd.org
Subject: Re: [Fwd: Re: FreeBSD Security Advisory FreeBSD-SA-03:12.openssh]
X-BeenThere: freebsd-security@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Security issues [members-only posting]
	<freebsd-security.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-security>,
	<mailto:freebsd-security-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-security>
List-Post: <mailto:freebsd-security@freebsd.org>
List-Help: <mailto:freebsd-security-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-security>,
	<mailto:freebsd-security-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 19 Sep 2003 01:36:37 -0000

Devon H. O'Dell just mooed:
>
> If I'm not mistaken, /dev/random is a pseudo-random generator, which 
> means it has a certain period before it begins to repeat numbers (along 
> with that it just isn't truly random). So, please correct me if I'm 
> wrong, but doesn't this mean that when reading from /dev/random, you're 
> 'losing' randomness/entropy/whatever you're calling it?

   You're mistaken.  /dev/random stops feeding you random bits
when it doesn't have enough.  /dev/urandom depletes the entropy
pool, but when it starts to run out, it falls back to hashing
to generate pseudo-random sequences from the random bits that
it can obtain.

  -Dave

-- 
work: dga@lcs.mit.edu                          me:  dga@pobox.com
      MIT Laboratory for Computer Science           http://www.angio.net/
      I do not accept unsolicited commercial email.  Do not spam me.