On Sat, Dec 08, 2007 at 06:46:12PM -0500, Theodore Tso wrote: > On Sun, Dec 09, 2007 at 12:10:10AM +0200, Ismail Dönmez wrote: > > > As long as /dev/random is readable for all users there's no reason to > > > use /dev/urandom for a local DoS... > > > > Draining entropy in /dev/urandom means that insecure and possibly not > > random > > data will be used and well thats a security bug if not a DoS bug. > > Actually in modern 2.6 kernels there are two separate output entropy > pools for /dev/random and /dev/urandom. So assuming that the > adversary doesn't know the contents of the current state of the > entropy pool (i.e., the RNG is well seeded with entropy), you can read > all you want from /dev/urandom and that won't give an adversary > successful information to attack /dev/random.
Wouldn't it be possible to mix the data with the pid+uid of the reading process so that even if another one tries to collect data from urandom, he cannot predict what another process will get ? BTW, I think that the tuple (pid,uid,timestamp of open) is unpredictable and uncontrollable enough to provide one or even a few bits of entropy by itself. Regards, Willy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
