I recently updated my SSL keys. Several servers are accessed by keys from a few devices. A common authorized_hosts file was created as a template. This post covers the generation and use of SSL keys.
WordPress SSH2 configuration
Instead of the packaged WordPress I run the version provided by WordPress. It is installed using a different userid from the userid the webserver runs as. To enable updates from the Admin Dashboard, I enabled sftp (ssh). This is how I did it.