Messages in this thread | | | Date | Mon, 12 Sep 2011 09:55:15 -0400 | From | Jarod Wilson <> | Subject | Re: [PATCH] random: add blocking facility to urandom |
| |
Valdis.Kletnieks@vt.edu wrote: > On Fri, 09 Sep 2011 10:21:13 +0800, Sandy Harris said: >> Barring a complete failure of SHA-1, an enemy who wants to >> infer the state from outputs needs astronomically large amounts >> of both data and effort. > > So let me get this straight - the movie-plot attack we're defending against is > somebody readin literally gigabytes to terabytes (though I suspect realistic > attacks will require peta/exabytes) of data from /dev/urandom, then performing > all the data reduction needed to infer the state of enough of the entropy pool > to infer all 160 bits of SHA-1 when only 80 bits are output... > > *and* doing it all without taking *any* action that adds any entropy to the > pool, and *also* ensuring that no other programs add any entropy via their > actions before the reading and data reduction completes. (Hint - if the > attacker can do this, you're already pwned and have bigger problems) > > /me thinks RedHat needs to start insisting on random drug testing for > their security experts at BSI. EIther that, or force BSI to share the > really good stuff they've been smoking, or they need to learn how huge > a number 2^160 *really* is....
Well, previously, we were looking at simply improving random entropy contributions, but quoting Matt Mackall from here:
http://www.mail-archive.com/linux-crypto@vger.kernel.org/msg05799.html
'I recommend you do some Google searches for "ssl timing attack" and "aes timing attack" to get a feel for the kind of seemingly impossible things that can be done and thereby recalibrate your scale of the impossible.'
:)
Note: I'm not a crypto person. At all. I'm just the "lucky" guy who got tagged to work on trying to implement various suggestions to satisfy various government agencies.
-- Jarod Wilson jarod@redhat.com
| |