It doesn't account for quantum computing? Cracking passwords seems like one of those things that should get an exponential speedup with quantum computing.
Becoming physically immune to brute-force attacks (2021)
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Re: Becoming physically immune to brute-force attacks (2021)
#22It doesn't account for quantum computing? Cracking passwords seems like one of those things that should get an exponential speedup with quantum computing.
Not exponential, cubic instead of quadratic.
Bigger issue in the context of this article is that it ignores reversible computing, which would nullify the core part of the thesis.
Re: Becoming physically immune to brute-force attacks (2021)
#23Loving reading this but.. 'TLDR - at the bottom' is wicked
There are a couple of other worthy jokes in the text, BTW.
Re: Becoming physically immune to brute-force attacks (2021)
#24Speaking of physically immune schemes, I remember some protocol which relied on a gigantic amount of data present behind a link that was, on purpose, very low bandwidth (physically low bandwidth: not by software as in rate limitation. That was the whole point: the link was physically low bandwidth). So the data was impossible to exfiltrate remotely: it simply wasn't physically possible to do remotely (it would be way…
The closest I can think of is ULF radio, which has two properties - extreme range and penetration, at the expense of extremely low bandwidth. My understanding is that it is used to communicate with underwater subs, but likely on the form of simple ascii or Morse code keywords.
Re: Becoming physically immune to brute-force attacks (2021)
#25Earlier quoted context omitted.
By "target system" you mean "system from which the password originated", right? But unless you think true randomness is impossible, and also that all possible sources of pseudo-random input on Earth come from terrestrial sources and not, say, incoming cosmic radiation, then knowing the size of the "Earth" system is no constraint at all. A heuristic for focusing your search, maybe, if you think the password is likely…
> By "target system" you mean "system from which the password originated", right? Yeah that’s correct. > The phrase "stored on Earth" is a red herring. You don't need to store all possible passwords for those passwords to be possible to generate here. A password used to protect a system must be persistently stored inside that system. The number of passwords that can be generated on earth is greater than the number th…
> A password used to protect a system must be persistently stored inside that system.
No it isn't; any system which is even remotely decent will only store the (usually salted) hash of passwords used on it.
Re: Becoming physically immune to brute-force attacks (2021)
#26Earlier quoted context omitted.
By "target system" you mean "system from which the password originated", right? But unless you think true randomness is impossible, and also that all possible sources of pseudo-random input on Earth come from terrestrial sources and not, say, incoming cosmic radiation, then knowing the size of the "Earth" system is no constraint at all. A heuristic for focusing your search, maybe, if you think the password is likely…
> By "target system" you mean "system from which the password originated", right? Yeah that’s correct. > The phrase "stored on Earth" is a red herring. You don't need to store all possible passwords for those passwords to be possible to generate here. A password used to protect a system must be persistently stored inside that system. The number of passwords that can be generated on earth is greater than the number th…
The password being persistently stored is not really a requirement here. That depends on the cryptosystem involved, among other things. What if I encrypt a ciphertext and throw away/forget the key?
Anyway, the constraint you're proposing here is, only passwords that can be encoded in all possible configurations of matter making up the earth? And you do have to contend with all possible configurations, if all you know is the size of the system, or even the mass and composition. As tedunangst put it, that's a lot of bits. I think we'll hit the 300-400 bit computational limit first.
Re: Becoming physically immune to brute-force attacks (2021)
#27This 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.
Re: Becoming physically immune to brute-force attacks (2021)
#28you don't need such complicated and hard to remember passwords--use something like bcrypt
Re: Becoming physically immune to brute-force attacks (2021)
#29Now do the wrench attack.
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Re: Becoming physically immune to brute-force attacks (2021)
#30It 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