From: Theodore Tso <tytso@mit.edu>
To: "Ismail Dönmez" <ismail@pardus.org.tr>
Cc: Adrian Bunk <bunk@kernel.org>, Bill Davidsen <davidsen@tmr.com>,
Marc Haber <mh+linux-kernel@zugschlus.de>,
linux-kernel@vger.kernel.org
Subject: Re: Why does reading from /dev/urandom deplete entropy so much?
Date: Sun, 9 Dec 2007 07:31:47 -0500 [thread overview]
Message-ID: <20071209123147.GZ17037@thunk.org> (raw)
In-Reply-To: <200712090821.16483.ismail@pardus.org.tr>
On Sun, Dec 09, 2007 at 08:21:16AM +0200, Ismail Dönmez wrote:
> My understanding was if you can drain entropy from /dev/urandom any futher
> reads from /dev/urandom will result in data which is not random at all. Is
> that wrong?
Past a certain point /dev/urandom will stat returning results which
are cryptographically random. At that point, you are depending on the
strength of the SHA hash algorithm, and actually being able to not
just to find hash collisions, but being able to trivially find all or
most possible pre-images for a particular SHA hash algorithm. If that
were to happen, it's highly likely that all digital signatures and
openssh would be totally broken.
- Ted
next prev parent reply other threads:[~2007-12-09 12:32 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-04 11:41 Why does reading from /dev/urandom deplete entropy so much? Marc Haber
2007-12-04 14:16 ` Eric Dumazet
2007-12-04 16:18 ` Adrian Bunk
2007-12-04 16:47 ` Alan Cox
2007-12-04 18:17 ` Eric Dumazet
2007-12-05 21:26 ` Matt Mackall
2007-12-06 7:02 ` Eric Dumazet
2007-12-06 16:09 ` Matt Mackall
2007-12-09 12:42 ` Marc Haber
2007-12-09 16:16 ` Matt Mackall
2007-12-10 23:06 ` Marc Haber
2007-12-10 23:35 ` Matt Mackall
2007-12-11 1:34 ` Theodore Tso
2007-12-11 19:46 ` Phillip Susi
2007-12-11 20:02 ` Ray Lee
2007-12-12 5:34 ` David Schwartz
2007-12-04 16:54 ` Ray Lee
2007-12-04 16:55 ` Alan Cox
2007-12-04 18:02 ` Matt Mackall
2007-12-04 19:50 ` Theodore Tso
2007-12-04 20:36 ` Matt Mackall
2007-12-04 20:40 ` Alan Cox
2007-12-04 20:48 ` Mike McGrath
2007-12-04 21:54 ` Matt Mackall
2007-12-04 22:03 ` Theodore Tso
2007-12-04 22:12 ` Mike McGrath
2007-12-04 22:28 ` Matt Mackall
2007-12-04 21:08 ` Matt Mackall
2007-12-04 21:18 ` Mike McGrath
2007-12-04 22:15 ` Matt Mackall
2007-12-04 22:23 ` Mike McGrath
2007-12-04 22:33 ` Matt Mackall
2007-12-05 14:26 ` Mike McGrath
2007-12-05 14:49 ` Theodore Tso
2007-12-08 7:38 ` Jon Masters
2007-12-08 17:32 ` Theodore Tso
2007-12-08 17:33 ` Mike McGrath
2007-12-08 17:49 ` Theodore Tso
2007-12-08 17:54 ` Jon Masters
2007-12-08 18:15 ` Matt Mackall
2007-12-08 18:24 ` Theodore Tso
2007-12-08 19:36 ` entropy gathering (was Re: Why does reading from /dev/urandom deplete entropy so much?) Jeff Garzik
2007-12-08 19:53 ` Matt Mackall
2007-12-08 20:04 ` Jeff Garzik
2007-12-08 20:19 ` Matt Mackall
2007-12-08 21:07 ` Willy Tarreau
2007-12-08 20:31 ` Theodore Tso
2007-12-08 20:47 ` Jeff Garzik
2007-12-08 20:42 ` Willy Tarreau
2007-12-08 23:47 ` Theodore Tso
2007-12-09 1:07 ` Jon Masters
2007-12-08 18:31 ` Why does reading from /dev/urandom deplete entropy so much? Jeff Garzik
2007-12-08 20:26 ` David Schwartz
2007-12-08 17:43 ` Matt Mackall
2007-12-08 17:47 ` Jon Masters
2007-12-08 18:05 ` Theodore Tso
2007-12-08 17:45 ` Jon Masters
2007-12-10 16:37 ` Pavel Machek
2007-12-04 18:01 ` Matt Mackall
2007-12-06 20:08 ` Bill Davidsen
2007-12-05 12:23 ` Marc Haber
2007-12-05 12:29 ` Marc Haber
2007-12-05 13:33 ` Theodore Tso
2007-12-05 15:10 ` Marc Haber
2007-12-06 19:32 ` Bill Davidsen
2007-12-08 22:03 ` Adrian Bunk
2007-12-08 22:10 ` Ismail Dönmez
2007-12-08 23:46 ` Theodore Tso
2007-12-09 5:21 ` Willy Tarreau
2007-12-09 6:52 ` Jon Masters
2007-12-09 6:21 ` Ismail Dönmez
2007-12-09 12:31 ` Theodore Tso [this message]
2007-12-09 14:06 ` Ismail Dönmez
2007-12-11 15:42 ` Bill Davidsen
2007-12-20 22:27 ` Marc Haber
2007-12-26 18:27 ` Phillip Susi
2007-12-04 18:49 ` Russ Dill
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20071209123147.GZ17037@thunk.org \
--to=tytso@mit.edu \
--cc=bunk@kernel.org \
--cc=davidsen@tmr.com \
--cc=ismail@pardus.org.tr \
--cc=linux-kernel@vger.kernel.org \
--cc=mh+linux-kernel@zugschlus.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.