Messages in this thread | | | Date | Tue, 16 May 2006 15:37:35 -0500 (CDT) | From | Chase Venters <> | Subject | Re: /dev/random on Linux |
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On Tue, 16 May 2006, Theodore Tso wrote: B> > 3) Investigate the possibility of adding quotas to /dev/random. This > is actually much more trickier that the paper suggests, since you want > to allow the user to be able to extract enough entropy to create a > 2048 bit (or at least a 1024-bit) RSA key. The problem is that's a > lot of entropy! Maybe it would be OK to only allow a 1024-bit RSA key > to be generated every 12 or 24 hours, but suppose someone is > experimenting with GPG and screws up (say they forget their > passphrase); do you tell them that sorry, you can't generating another > key until tomorrow? So now we have to have an interface so the root > user can reset the user's entropy quota.... And even with a 24-hour > limit, on a diskless system, you don't get a lot of entropy, so even a > 1024-bit RSA key could seriously deplete your supply of entropy.
#3 is fine if it's out of the kernel. This isn't just policy - it's complicated policy, as you point out quite well.
> This last point is a good example of the concerns one faces when > trying to design a working system in the real word, as opposed to the > concerns of academicians, where the presence or lack of forward > security in the event of a pool compromise is issue of massive urgency > and oh-my-goodness-we-can-only-tell-the-maintainer-because-it's-such-a- > critical-security-hole attitude. Where as my attitude is, "yeah, we > should fix it, but I doubt anyone has actually been harmed by this in > real life", which puts it in a different category than a buffer > overrun attack which is accessible from a publically available network > service. >
Slashdot headline about Linux's weak-ass rng should be up shortly, next to the news post discussing what Linus had for breakfast this morning.
> - Ted
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