That's a really interesting point actually. A hash of IPv6 would essentially be technically infeasible to brute force if fed through something like scrypt. But

That's a really interesting point actually. A hash of IPv6 would essentially be technically infeasible to brute force if fed through something like scrypt. But it wouldn't be exactly 128 bit random, since they could do a search based on the addresses allocated. I'd need to know the size of that potential pool to know how hard that would be, but if it's already in the dozens of billions, it's pretty difficult.