Messages in this thread | | | Date | Sun, 18 May 2008 08:57:59 -0400 | From | Joe Korty <> | Subject | Re: [PATCH] Re: [PATCH] drivers/net: remove network drivers' last few uses of IRQF_SAMPLE_RANDOM |
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On Sun, May 18, 2008 at 07:26:57AM -0400, Theodore Tso wrote: > On Sun, May 18, 2008 at 12:13:35PM +0200, Andi Kleen wrote: > > We don't use it for most long term keys, e.g. ssh host keys. That is > > because even on high entropy systems /dev/random usually doesn't work > > during distribution installation because the system has not run long > > enough to collect significant entropy yet. > ... > Hence, if you don't think the system hasn't run long enough to collect > significant entropy, you need to distinguish between "has run long > enough to collect entropy which is causes the entropy credits using a > somewhat estimation system where we try to be conservative such that > /dev/random will let you extract the number of bits you need", and > "has run long enough to collect entropy which is unpredictable by an > outside attacker such that host keys generated by /dev/urandom really > are secure". > ... > If distributions really cared, they could very well introduce keyboard > banging as part of the install process; but no, being able to do an > unmanned, "turnkey" install is considered more important. That says > something about how much they care about security right there.
If the World really cared about security, every cpu chip would supply a true source of random bits based on the sampling some easily accessable quantum on-chip state, such as the tiny fluctuations in current flow across a resistance. I suspect supplying this would be about as expensive as supplying a true TSC driven directly by the external clock -- that is, so close to zero as to not matter.
Joe
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