Use passphrase terminology, not PIN

[dcousens]

As part of f8a5360, you used the phrasing passphrase, not PIN; and the usage seems inconsistent throughout.

This pull request replaces any usage of pin with passphrase (or pass internally), such that the usage and terminology (and stdout output) is somewhat consistent with ssh-keygen.

I think pointing out that TPM 2.0 has well defined anti-hammering protection is informative as to the type of passphrase you could use compared to hinting specifically that you have PIN support; which nearly sounds like a limitation to me than a feature.

However I am not too opinionated on keeping ce6edea in this pull request if you feel otherwise.

[Foxboron]

The issue is that passphrase implies that you write a longer passphrase. The point of using "PIN" to tell people that with DA procetion you can have a 4 digit numerical pin as protection for the key. Writing "TPM Passphrase" does not convey this.

The reason why it says so in the askpass prompt is because there are askpass programs that cache the "passphrase" based off on the "askpass" prompt. Thus you end up with inconsistentcies like this.

So I'm not really convinced I want all of these changes.

[dcousens]

That's fair, and I'm thinking about how maybe we can balance the best of both.
I'll mark this as draft for now, unless you only wanted me to drop ce6edea?

[Foxboron]

I'll need to think a bit. Internally in the codebase I think it's better to use userauth instead of pin or pass to better convey what it actually is in the context of the TPM.

[Foxboron]

Okay, I've decided.

Drop the change from "pin" to "pass" in the codebase as I plan on changing the references to "userauth" which is the correct word in the context of TPMs.

I think we should drop the README.md change and I'll ponder on a better sentence. The prompt changes from "pin" to "passphrase" to keep it consistent with openssh is fine.

Does all of that sounds fine?

[dcousens]

@Foxboron I think I have made the changes requested, should be good for review

[dcousens]

I additionally added d45fd23, which seems to be different - I can drop that if needed