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From: "Jörn Engel" <joern@logfs.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Stephan Mueller <smueller@chronox.de>,
	Linux Kernel Developers List <linux-kernel@vger.kernel.org>,
	"Maciej W. Rozycki" <macro@linux-mips.org>,
	Ralf Baechle <ralf@linux-mips.org>,
	dave.taht@gmail.com, John Crispin <blogic@openwrt.org>,
	andrewmcgr@gmail.com, Thorsten Glaser <tg@mirbsd.de>,
	sandyinchina@gmail.com
Subject: Re: [RFC PATCH 0/5] CPU Jitter RNG
Date: Mon, 10 Feb 2014 16:07:44 -0500	[thread overview]
Message-ID: <20140210210744.GA9137@logfs.org> (raw)
In-Reply-To: <52F15000.2080102@zytor.com>

On Tue, 4 February 2014 12:39:28 -0800, H. Peter Anvin wrote:
> 
> USB and the Ethernet PHY frequently do still have their own crystals,
> for reasons not entirely clear to me.  However, what all of these have
> in common is that they are way out in the periphery.

Storage might be another source.  We have had add_disk_randomness()
forever.  Flash also takes quite variable timings for writes and
erases.  Even if the timings are not random, they certainly change
from block to block and depending on wear.

I am less certain about reads.  But one can run a few experiments and
see how consistent the timings are.

Jörn

--
Linux is more the core point of a concept that surrounds "open source"
which, in turn, is based on a false concept. This concept is that
people actually want to look at source code.
-- Rob Enderle

  parent reply	other threads:[~2014-02-10 21:07 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-04 12:36 [RFC PATCH 0/5] CPU Jitter RNG Stephan Mueller
2014-02-04 12:39 ` [PATCH 1/5] " Stephan Mueller
2014-02-04 12:40 ` [PATCH 2/5] CPU Jitter RNG: Enable compilation Stephan Mueller
2014-02-04 13:39   ` Geert Uytterhoeven
2014-02-04 16:19     ` Stephan Mueller
2014-02-04 16:39       ` Hannes Frederic Sowa
2014-02-04 16:50         ` Hannes Frederic Sowa
2014-02-04 16:53         ` Stephan Mueller
2014-02-04 17:15           ` Hannes Frederic Sowa
2014-02-04 12:40 ` [PATCH 3/5] CPU Jitter RNG: integration with /dev/random Stephan Mueller
2014-02-04 12:41 ` [PATCH 4/5] CPU Jitter RNG: provide status proc files Stephan Mueller
2014-02-04 12:42 ` [PATCH 5/5] CPU Jitter RNG: add read/write sysctls Stephan Mueller
2014-02-04 17:08 ` [RFC PATCH 0/5] CPU Jitter RNG Theodore Ts'o
2014-02-04 19:06   ` H. Peter Anvin
2014-02-04 19:23     ` tytso
2014-02-04 19:39       ` Geert Uytterhoeven
2014-02-04 20:39         ` H. Peter Anvin
2014-02-04 21:46           ` Geert Uytterhoeven
2014-02-04 21:47             ` H. Peter Anvin
2014-02-10 21:07           ` Jörn Engel [this message]
2014-02-04 20:31     ` Stephan Mueller
2014-02-04 21:34       ` H. Peter Anvin
2014-02-04 21:43       ` Geert Uytterhoeven
2014-02-04 20:25   ` Stephan Mueller

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