Setting-up keys with putty

  
On UNIX(tm):
$ cd ~/.ssh
$ ssh-keygen -t rsa
$ cp id_rsa.pub authorized_keys

On Windows(tm):
- scp user@unixsystem:~/.ssh/id_rsa ./
- puttygen conversion - import key - <id_rsa> - save private key - <ux-key.ppk> - file - exit
- putty configuration - connection - ssh - auth - pki. file for auth (ux-key.ppk).
- <save putty default config>

test putty connection...

For other unix systems you distribute the authorized_keys but make sure your homedir has correct permissions (chmod 750).