Root Access With SSH - PermitRootLogin or PasswordAuthentication

Hi,

I just did a one click install of MongoDB. I’m SSH into the machine and its all ok.

Now, I want to disable password to the machine to prevent brute force, however two different articles are stating two different things to achieve this:

Is it:

PasswordAuthentication no 

OR

PermitRootLogin without-password

The later, I can’t actually see this in my /etc/ssh/sshd_config file.

Also by doing this I presume if I access the console via the Digital Ocean page, I can still use the password to login?

If not, then what would happen the certs on my machine went missing?

Thanks.