That's... not reassuring. Though I would still argue that that is more of an implementation issue, not a deal-breaker for the general idea. And there are many K

That's... not reassuring. Though I would still argue that that is more of an implementation issue, not a deal-breaker for the general idea. And there are many KDF variants that (claim to) offer protection against brute force, so that's not necessarily an issue either (but I do agree it sounds risky).