how to secure RMAN scripts?

NBU 7.6.0.3

this may sound silly but i need the opinion of the experts please.  when NBU does Oracle database backup, it calls the RMAN script. this RMAN script contains instructions on how to backup and what to backup. it also contains login credentials for the account (sys) allowed to access the database.

questions:

1. since the RMAN script is in plain text, is it possible to protect it while being called by NBU?
2. can the login credentials be specified NOT in the RMAN script, but elsewhere, in order to protect it?

regards,

Reno