On 31.07.2013 4:07, David O'Brien wrote: > I believe you're talking about this code in > sys/libkern/arc4random.c:arc4rand() > > if (atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_HAVE, > ARC4_ENTR_SEED) || reseed || > (arc4_numruns > ARC4_RESEED_BYTES) || > (tv.tv_sec > arc4_t_reseed)) > arc4_randomstir(); > > Without setting 'arc4rand_iniseed_state' from ARC4_ENTR_NONE -> > ARC4_ENTR_HAVE, we would still call arc4_randomstir() periodically due > to (tv.tv_sec > arc4_t_reseed) and (arc4_numruns > ARC4_RESEED_BYTES).
The whole problem is that arc4 is poorly initialized right after boot, but immediately used in many places like tcp. It reseeds again only after 5 minutes after boot making vulnerability window at this interval. > But, this situation isn't the big issue. We have an existing bug where > if one is using a hardware RNG, read_random() never gets changed from > simply being read_random_phony() due to random_modevent() not calling > random_yarrow_init_harvester() thru '(*random_systat->init)()'. Thus > arc4random() has been weak for thus using the Intel RDRAND or Via > Padlock. I don't fix hardware RNG parts due to missing hardware for tests. They should have the same line as randomdev_soft.c somewhere. -- http://ache.vniz.net/ bitcoin:1G6ugdNY6e5jx1GVnAU2ntj2NEfmjKG85r _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
