I currently use OpenSSH to access a set of machines that I am not root on (the 
servers run OpenSSH too). Authentication is by one of keys or passwords 
entered at the keyboard. I want to be able to indicate that for my account, 
only key based authentication is permissible, without impacting on other users 
of the account. I've not been able to find a way to do this via the current 
sshd. 
 
The idea is to add a per-user file, which can be used to indicate which 
authentication methods the user does not want to use; sshd would then accept 
only those methods that are allowed by the sysadmin in sshd_config, and not 
blocked by the user in this file.