Oracle 11 Encrypted tablespaces

Start of the Oracle 11 you can create encrypted tablespaces.
But you can't alter tablespaces to encrypted. So if you need to
encrypt tablespace you need always create new one with encryption on.

Encrypted tablespaces are created like this:
SQL> CREATE TABLESPACE test_enc_ts DATAFILE '/data/oradata/testdb/test_enc_ts_01.dbf'
size 512M encryption using '3DES168' default storage (encrypt);

If you don't use "using 'encryption_algorithm'" clause then
default algorithm (AES128) is used.

You can check if tablespace is encrypted from DBA_TABLESPACES view ENCRYPTED column.

Tablespace encryption will slow down DML and SQL operations but it
allows you to use indexes in all columns on it. If you encrypt only single column
in one table Oracle won't use index with that column. So in those cases
tablespace encryption is better than single column encryption.