Re: [PATCH] random: add blocking facility to urandom
|[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]|
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@xxxxxxxxxxxxxxx/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@xxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html