Passwordless SSH login

[Bob]

I have set up SSH between two computers on my LAN and am trying to disable
password login.  SSH works between the computers.  I can login using
public/private keys.  What I have not been able to do is disable the password
login.

The instructions I am using
<https://www.linuxbabe.com/linux-server/setup-passwordless-ssh-login> says to
edit /etc/ssh/sshd_config and change "PasswordAuthentication" from "yes" to
"no" and change "ChallengeResponseAuthentication" to "no".  That did not work
as I can still SSH to the computer and login to the computer using the
password.

When I edit /etc/ssh/sshd_config "PasswordAuthentication" is commented out so I
removed the comment and changed "yes" to "no". 
"ChallengeResponseAuthentication" was not on the config file so I added it. 
What else do I need to do?

-- 
Robert Blair


We hang the petty thieves and appoint the great ones to public office.  -- Aesop