Ignoramus7715 wrote:
> If an intruder gets sufficient privileges to get a hold of actual
> keys, they would likely be able to find out su passwords, as well.

This is not necessarily true if you keep the key on a medium which can
be physically stolen, like a USB pen. In any case it might be useful to
have two versions of the key. One is encrypted with a passphrase and you
can keep this on a less secure medium and the unencrypted key can be
used for automated backups from a secure medium.

Steven