Unhelpful SSH Key Addition

Hi,

I'm trying to add my SSH key to the configuration since simply adding this to authorized_keys gets nuked on a reboot or whenever the router feels like it.

I've tried adding the key through the web configuration, it fails and won't tell me why. I've tried adding a key through the CLI interface and I continually get this:

loadkey ubnt /tmp/ubnt.pub
Not a valid key file format (see man sshd) at /opt/vyatta/sbin/vyatta-load-user-key.pl line 96, <$in> line 1.

I'm somewhat mystified as to the format it's expecting. I've tried a standard public SSH key format of:

---- BEGIN SSH2 PUBLIC KEY ----
Comment: "...."

---- END SSH2 PUBLIC KEY ----

With the key below the comment line. I've tried the authorized_keys format of:

ssh-rsa key.......

Still the same result. This is a public key that's been used on countless servers and also added into the authorized_keys file on this Edgemax and used to log in before the last firmware update that keeps wiping authorized_keys.

What weird and wonderful public SSH key format is this Perl script expecting?

Thanks,