630.Which two statements are true about encrypting RMAN backup? (Choose two.)
A. The transparent encryption of backups uses the encryption wallet
B. The database uses the same encryption key for every encrypted backup
C. The password encryption of backups only uses the password while creating and restoring backup
D. If transparent encryption is configured, you cannot use the SET ENCRYPTION BY PASSWORD
command to make password-protected backups.
Answer: AC

可以同时使用transparent encryption与password encryption

参考：http://blog.csdn.net/rlhua/article/details/12312463