we can encrypt any rman backup in the form of a backup set.
we can encrypt in two ways ie transport and password encryption
Password Encryption:
$export ORACLE_SID=TEMP
$rlwrap rman target sys/oracle
rman>set encryption on identified
Here i am choosing encryption on tablespace ie users
rman>configure encryption for tablespace users on;
rman>sql'alter tablespace users offline';
rman>restore tablespace users;
failed we need to
Rman>set decryption identified by
Rman>restore tablespace users;
rman> recover tablespace users;
rman>sql'alter tablespace users online';