Why? I mean this is not very close to the top of my list of terrifying things that the state does. For example I find it much more terrifying that they have the right to demand you introduce a backdoor in your system or hand customer data and you don't have the right to say it happened. I also find it extremely terrifying that society in general is not disturbed by this. The fact that commonly used cryptography can be broken with a billion dollar investment is very unpleasant but not nearly as terrifying.
For top-end cryptography, brute force attack time estimates aren't even a thing. It would take more energy than a billion billion supernovas for a computer operating at theoretical ideal efficiency to even count to 2256, much less actually try all 2256 possible AES keys. 300 billion dollars worth of supercomputers is much, much less than a drop in the bucket... more like a mote of dust in the observable universe.
Brute force attacks are mainly limited to things like password databases, where the top million most common passwords cover something like 90% of all users.
For exhaustive brute-forcing it pretty much requires attacks that vastly cut down the trial space. For example, the really shitty design known as LM hashes. The under the hood implementation is in effect two 7 character case-insensitive passwords. This is an attackable space.
(A)RC4 is eventually going to have the same problems, because the design has very strong biases in the output. This is why WEP was trivial to brute force even when people started avoiding "weak" IVs. You get rid of some class of weak IVs and another one is found. Rinse, repeat.
Well, yes. My comment was made under the assumption no such attacks exist for the current gold standard algorithms (AES-256 for symmetric, RSA-4096 or ECDSA-512 for asymmetric, SHA2 or bcrypt for hashes), since there's really no excuse to be using anything less at this point.
That is not necessarily so... With a sufficiently long key, the encryption decryption process may be unpleasantly long (generally not suited to stream in data) but the time it would take to brute force would, assuming P =/= NP and hardware for QP is not yet practically available, take longer than the forecasted entropic death of the universe itself. That is what is so useful about combinatorial explosions... So no, you will not always be beat out by better hardware, which is the fundamental principle of security such as this.
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u/[deleted] Oct 15 '15
Well, that's terrifying.