Using `keybase prove` anything just hangs.

On OS X 10.10

```
me@computer $ keybase prove hackernews
info: Updated file: /Users/me/.cache/keybase/session.json
Your username on HackerNews (**case sensitive**): dalanmiller

You need a passphrase to unlock the secret key for
user: "keybase.io/dalanmiller "
2048-bit RSA key, ID 4DB8A56BCF5BA409, created 2014-10-24
(subkey on main key ID 4A9FDC89766AD887)

```

After staying here, nothing happened for a very long amount of time. I did the online version of the Twitter prove and it took no time at all.

Is there something happening in the background? It asks for a passphrase but as I type, my input is not masked?

Start by reproducing `keybase prove hackernews` on OS X 10.10 and observe the passphrase prompt and whether input is accepted. Trace the `keybase prove` entry point and the passphrase handling; done when the command no longer hangs or clearly reports the required interaction.

Written by the indexing model from the issue text.