Reply to comment:
Does not compute. Article says: "only 50 out of all the MNTNER objects in the RIPE Database do not use passwords as an authentication mechanism." *But* it also says "A further 1,507 contained only PGP keys and no other methods. And 21 contained only X.509 certificate IDs and no other methods." So that's at least 1528 MNTNER objects that don't use passwords.