On Aug 16, 2002 19:45 -0500, Oliver Xymoron wrote:
> Realistically, the hashing done by /dev/urandom is probably strong
> enough for most purposes. It's as cryptographically strong as whatever
> block cipher you're likely to use with it. /dev/random goes one step
> further and tries to offer something that's theoretically
> unbreakable. Useful for generating things like large public keys, less
> useful for generating the session keys used by SSL and the
> like. They're easier to break by direct attack.
One of the problems, I believe, is that reading from /dev/urandom will
also deplete the entropy pool, just like reading from /dev/random.
The only difference is that when the entropy is gone /dev/random will
stop and /dev/urandom will continue to provide data.
If you are in there fixing things, it might make sense to have
/dev/urandom extract entropy from the random pool far less often than
/dev/random. This way people who use /dev/urandom for a source of
less-strong randomness (e.g. TCP sequence numbers or whatever), will
not be shooting themselves in the foot for when they need a 2048-byte
PGP key, if they are low on entropy sources.
Cheers, Andreas
-- Andreas Dilger http://www-mddsp.enel.ucalgary.ca/People/adilger/ http://sourceforge.net/projects/ext2resize/- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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