> A password with 327 bits of entropy is nearly impossible to crack even if you burn the whole observable universe trying to do so.
This is exactly the question I was asking me when starting the article, and it is answered perfectly.
Becoming physically immune to brute-force attacks (2021)
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Re: Becoming physically immune to brute-force attacks (2021)
#42Is this proof that the universe cannot understand itself? It seems weird that there can be a set of information in the universe that can be hidden from the rest of the universe.
It seems kinda vital to me - there needs to be an informational bottleneck somewhere.
Re: Becoming physically immune to brute-force attacks (2021)
#43> An excerpt from a religious text with a trailing space:
> "I'd just like to interject for a moment. What you’re referring to as Linux, is in fact, GNU/Linux,"
Re: Becoming physically immune to brute-force attacks (2021)
#44I can't say I understood and evaluated all the physics here (I skimmed parts) but I was pretty surprised by how small the estimate was. I would've assumed that, were we to have one or two thousand years more cryptographic history, we'd end up using ginormous keys (maybe on the order of 1 MiB?). But this suggests that 512 or 1024 bits might be all we need.
This is because exponential growth is counter-intuitive. A 256 bit key is not 2x more secure than 128 bit, it is 340282366920938463463374607431768211456x more secure.
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Re: Becoming physically immune to brute-force attacks (2021)
#45It doesn't account for quantum computing? Cracking passwords seems like one of those things that should get an exponential speedup with quantum computing.
From what I read, trying to crack AES 256 with quantum is like cracking 128, so impossible
History is pretty good at showing presumed-impossible things to indeed be possible.
Re: Becoming physically immune to brute-force attacks (2021)
#46I could be wrong (my physics background isn't that strong either) but I think Dyson's "time without end" paper http://www.aleph.se/Trans/Global/Omega/dyson.txt shows that eventually the universe will cool down enough to make all keys brute-force-attackable despite Bremermann's limit. Given a finite amount of attacker computation you're willing to defend against, you can get a real advantage from key stretching (thoug…
Technically bcrypt isn't a KDF.
Re: Becoming physically immune to brute-force attacks (2021)
#47This is probably a decent estimate, but there's a couple of routes of attack it fails to account for. First it uses the current average temperature of the universe. Lowering the temperature can be done by just waiting a while before turning the machine on. I assume that powering a sufficiently powerful fridge is not an option, given the origin of the theoretical limit, but I can't quite point out why it wouldn't work…
If you wait for the temperature to drop, and the universe is expanding, distant galaxies will recede to the point that they are now moving away faster than the speed of light and their matter is no longer available to contribute.
Thank it is expanding now really means that it will expand forever? Are there not other physics at play that could stop that at some point, yeah I don't know much about any of this just wondering out loud.
Re: Becoming physically immune to brute-force attacks (2021)
#48Is this proof that the universe cannot understand itself? It seems weird that there can be a set of information in the universe that can be hidden from the rest of the universe.
Not entirely. Cryptographic primitives are based on hardness assumptions. For example, we assume discrete log cannot be computed in probabilistic polynomial time when we leverage things like Diffie Hellman. No one has yet proven whether this assumption (and many others like it) is true or false, but so many people way smarter than you or I have tried and not made much headway and so it's safe enough to rely on it.
If someone were to prove one of these assumptions is true, then I suppose the answer to your question is yes, but I wouldn't hold my breath waiting for such a proof :)
Re: Becoming physically immune to brute-force attacks (2021)
#49Is this proof that the universe cannot understand itself? It seems weird that there can be a set of information in the universe that can be hidden from the rest of the universe.
> Is this proof that the universe cannot understand itself?
What does “understanding” means when talking about an inanimate thing?
> It seems weird that there can be a set of information in the universe that can be hidden from the rest of the universe.
Why should the rest of the universe “know” anything about other parts of the universe?
Ascribing “understanding” and “knowledge” to the universe sounds questionable from the start, it doesn't seem weird to me that the universe doesn't have these properties.
Re: Becoming physically immune to brute-force attacks (2021)
#50I can't say I understood and evaluated all the physics here (I skimmed parts) but I was pretty surprised by how small the estimate was. I would've assumed that, were we to have one or two thousand years more cryptographic history, we'd end up using ginormous keys (maybe on the order of 1 MiB?). But this suggests that 512 or 1024 bits might be all we need.
That assumes that the best you can do is brute force, but real encryption algorithms (even AES) are weaker than that, so the attacker can infer some bits of the key. More so for asymmetric encryption.