From: "David Jaša" <djasa@redhat.com>
To: "Theodore Ts'o" <tytso@mit.edu>
Cc: Stephan Mueller <smueller@chronox.de>,
Andi Kleen <andi@firstfloor.org>,
sandyinchina@gmail.com,
Jason Cooper <cryptography@lakedaemon.net>,
John Denker <jsd@av8n.com>,
"H. Peter Anvin" <hpa@linux.intel.com>,
Joe Perches <joe@perches.com>, Pavel Machek <pavel@ucw.cz>,
George Spelvin <linux@horizon.com>,
linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 0/5] /dev/random - a new approach
Date: Tue, 21 Jun 2016 14:25:36 +0200 [thread overview]
Message-ID: <1466511936.9421.18.camel@redhat.com> (raw)
In-Reply-To: <20160618144408.GA5344@thunk.org>
Hi,
On So, 2016-06-18 at 10:44 -0400, Theodore Ts'o wrote:
> On Fri, Jun 17, 2016 at 03:56:13PM +0200, David Jaša wrote:
> > I was thinking along the lines that "almost every important package
> > supports FreeBSD as well where they have to handle the condition so
> > option to switch to Rather Break Than Generate Weak Keys would be nice"
> > - but I didn't expect that systemd could be a roadblock here. :-/
>
> It wasn't just systemd; it also broke OpenWRT and Ubuntu Quantal
> systems from booting.
>
> > I was also thinking of little devices where OpenWRT or proprietary
> > Linux-based systems run that ended up with predictable keys way too
> > ofter (or as in OpenWRT's case, with cumbersome tutorials how to
> > generate keys elsewhere).
>
> OpenWRT and other embedded devices (a) generally use a single master
> oscillator to drive everything, and (b) often use RISC architectures
> such as MIPS.
>
> Which means that arguments of the form ``the Intel L1 / L2 cache
> architecture is ****soooo**** complicated that no human could possibly
> figure out how they would affect timing calculations, and besides, my
> generator passes FIPS 140-2 tests (never mind AES(NSA_KEY, CNTR++)
this
> also passes the FIPS 140-2 statistical tests)'' --- which I normally
> have trouble believing --- are even harder for me to believe.
>
> At the end of the day, with these devices you really badly need a
> hardware RNG.
and this.
It seems much easier to me to embed AES(NSA_KEY, CNTR++) logic directly
to HW RNG compared to tweaking of every microarchitecture to make
jitter/maxwell/havege return known numbers that are going to be mixed
with other entropy anyway (won't they?). So if I put the bits together
correctly, HW RNG helps getting more random numbers but itself is
insufficient to ensure that random numbers are truly random...
Cheers,
David Jaša
> We can't generate randomness out of thin air. The only
> thing you really can do requires user space help, which is to generate
> keys lazily, or as late as possible, so you can gather as much entropy
> as you can --- and to feed in measurements from the WiFi (RSSI
> measurements, MAC addresses seen, etc.) This won't help much if you
> have an FBI van parked outside your house trying to carry out a
> TEMPEST attack, but hopefully it provides some protection against a
> remote attacker who isn't try to carry out an on-premises attack.
>
> Cheers,
>
> - Ted
prev parent reply other threads:[~2016-06-21 12:25 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-31 18:37 [PATCH v4 0/5] /dev/random - a new approach Stephan Mueller
2016-05-31 18:37 ` [PATCH v4 1/5] crypto: DRBG - externalize DRBG functions for LRNG Stephan Mueller
2016-05-31 18:38 ` [PATCH v4 2/5] random: conditionally compile code depending on LRNG Stephan Mueller
2016-05-31 18:39 ` [PATCH v4 3/5] crypto: Linux Random Number Generator Stephan Mueller
2016-05-31 18:39 ` [PATCH v4 4/5] crypto: LRNG - enable compile Stephan Mueller
2016-05-31 18:39 ` [PATCH v4 5/5] random: add interrupt callback to VMBus IRQ handler Stephan Mueller
2016-05-31 22:34 ` [PATCH v4 0/5] /dev/random - a new approach George Spelvin
2016-06-15 16:17 ` David Jaša
2016-06-15 16:58 ` Stephan Mueller
2016-06-17 13:56 ` David Jaša
2016-06-17 15:26 ` Sandy Harris
2016-06-18 8:22 ` Stephan Mueller
2016-06-18 8:21 ` Stephan Mueller
2016-06-18 14:44 ` Theodore Ts'o
2016-06-18 16:31 ` Stephan Mueller
2016-06-20 17:07 ` Austin S. Hemmelgarn
2016-06-20 18:32 ` Stephan Mueller
2016-06-21 13:05 ` Austin S. Hemmelgarn
2016-06-21 13:19 ` Tomas Mraz
2016-06-21 17:18 ` Austin S. Hemmelgarn
2016-06-21 17:23 ` Stephan Mueller
2016-06-21 17:54 ` Austin S. Hemmelgarn
2016-06-21 18:05 ` Stephan Mueller
2016-06-21 13:20 ` Stephan Mueller
2016-06-21 17:51 ` Austin S. Hemmelgarn
2016-06-21 18:04 ` Stephan Mueller
2016-06-21 19:31 ` Austin S. Hemmelgarn
2016-06-22 5:16 ` Stephan Mueller
2016-06-22 12:54 ` Austin S. Hemmelgarn
2016-06-22 13:25 ` Stephan Mueller
2016-06-21 13:42 ` Pavel Machek
2016-06-21 17:17 ` Austin S. Hemmelgarn
2016-06-21 12:25 ` David Jaša [this message]
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