can sudo use SSH passphrase rather than user sys passwd ?

[atherios at free.fr]

Hi,

I setup SSHv2 key authent to connect to servers.
Each guys can run priviledged commands via sudo.
The trouble is that, as they log via SSH key only, they don't
have a 'real' system password. But sudo (seems to) requires
a password to run the priviledged command.

Can I tell sudo to authenticated the user throught he's SSH key ?
This is, can sudo validate the ssh passphrase rather than the system passwd.

Thankfs for answers