Linux

AFAIK:
If you want the users to type a password for sudo, then they must have a password for their own account.
Where there is no password for one owns account, it cannot be entered upon sudo, however, one can have an account with password with a passwordless sudo.

Another idea, but i dont know how to implement, would be ssh-key files.
See: ssh-keygen and probably ssh-copy-id of openssh package for more details.

Hope this helps to get you started.