Paste warning should not show password in secure input/padlock mode

[cryptocode]

In the image below (where I've cut off the password) I pasted a password with special characters for an ssh session, while in secure input "padlock mode"

The macOS secure input and padlock is a great feature that doesn't echo the password, so it's a bit of a bummer that the paste warning shows the password in clear text.

I feel like the warning should be suppressed, or at least not show the pasted value when in padlock mode.

[mitchellh]

This is a very good suggestion. I think showing the unsafe paste warning is still valuable, but we should probably mark it as sensitive and have the UI behave accordingly. Thoughts?

[cryptocode]

That sounds good, e.g show the warning but hide sensitive data in secure input mode, and then maybe have a reveal button (eye icon or something) if the user wants to see it.

[mitchellh]

#4947