[Database]

I’m not exactly a “Crypto Whiz Kid” but I’ll give it a go.

Current crypto systems are based on functions that can be computed quickly in one direction, but are hard (meaning not computationally practical) to compute in the other direction. The threat here is that quantum computing would be able to do the reverse computation quickly.

So, checking for success is not necessary and counting breakin attempts would not help. Just calculate the key and use it.

[InterceptPoint]

So, checking for success is not necessary and counting breakin attempts would not help. Just calculate the key and use it.
+++++
Thanks for your input. What to say makes sense. If that is the way they now do it they are vulnerable.

But why use a system like that once it’s “broken”? Just use very long encryption passwords and limit the number of tests for success. Old fashioned, probably cumbersome but I don’t think a quantum computer breaks it.

[Enlightened1]

Well said!

[Svartalfiar]

So, checking for success is not necessary and counting breakin attempts would not help. Just calculate the key and use it.

And what do you calculate the key from? That works fine if you have the lockbox and full access, but that doesn't help when you're submitting login attempts remotely. Likewise, if you're intercepting encrypted passwords and/or hashes, sure you can break those but there's probably several different results for any given hash (many of which make sense when a password can just be a string or random chars), so how do you know which one is correct?