Comment on Password manager by Amazon
Cocodapuf@lemmy.world 6 days agoMy understanding is that quantum competing has been taken into account for some moment cryptography. And that memory-hard cryptography basically defeats quantum competing solutions. There are a few methods, but one of them is just very long keys, it’s trivial to make a cryptographic key longer.
So sure, you could defeat some of that with a machine operating with 1024k entangled qbits, (which is… oh man… not an easy task), in which case, wow, congratulations. But what if I increase my key length to 100k? It might take an extra 3 seconds to check the key and log in, but it’ll take an extra 25 years for quantum computing to catch up.
Toribor@corndog.social 6 days ago
Won’t longer key lengths increase the overhead for everything?
procrastitron@lemmy.world 6 days ago
Yes and No.
Yes, everything increases in difficulty but the increases in difficulty are asymmetrical.
The difficulty of reversing a computation (e.g. reversing a hash or decrypting an encrypted message) grows much faster than just performing the computation (e.g. hashing a message or encrypting one).
That’s the basis for encryption to begin with.
It’s also why increasing the size of the problem (e.g. the size of the hash or the size of a private key) makes it harder to crack.
The threat posed by quantum computing is that it might be feasible to reverse much larger computations than it previously was. The caveat on that, however is that they have a hard limit of what problems they can solve based on the number of qbits they have.
So for example, let’s say you use RSA for encryption and someone builds a 1024 qbit quantum computer. All you have to do is increase your key size so that it would require 1025 qbits to crack, and then that quantum computer wouldn’t provide an attacker any benefit at all.
(Of course, they’d still be able to read your old messages, but that’s also a fundamental principle of cryptography; it only protects you for a period of time)