On Tue, Dec 04, 2007 at 07:17:58PM +0100, Eric Dumazet wrote: > Alan Cox a ?crit : > >>No matter what you consider as being better, changing a 12 years old and > >>widely used userspace interface like /dev/urandom is simply not an > >>option. > >> > > > >Fixing it to be more efficient in its use of entropy and also fixing the > >fact its not actually a good random number source would be worth looking > >at however. > > > Yes, since current behavior on network irq is very pessimistic.
No, it's very optimistic. The network should not be trusted. The distinction between /dev/random and /dev/urandom boils down to one word: paranoia. If you are not paranoid enough to mistrust your network, then /dev/random IS NOT FOR YOU. Use /dev/urandom. Do not send patches to make /dev/random less paranoid, kthxbye. > If you have some trafic, (ie more than HZ/2 interrupts per second), > then add_timer_randomness() feeds > some entropy but gives no credit (calling credit_entropy_store() with > nbits=0) > > This is because we take into account only the jiffies difference, and > not the get_cycles() that should give > us more entropy on most plaforms. If we cannot measure a difference, we should nonetheless assume there is one? > In this patch, I suggest that we feed only one u32 word of entropy, > combination of the previous distinct > words (with some of them being constant or so), so that the nbits > estimation is less pessimistic, but also to > avoid injecting false entropy. Umm.. no, that's not how it works at all. Also, for future reference, patches for /dev/random go through me, not through Dave. -- Mathematics is the supreme nostalgia of our time. -- 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/
