Encrypt Table Column

Once table column is encrypted, as sysdba, I still can see the encrypted data in text mode. 

And if to close the wallet, the column will not able to view.

SQL> select * from encryp_t;
select * from encryp_t
*
ERROR at line 1:
ORA-28365: wallet is not open

And according to the user guide --> In most cases, leave the wallet open unless you have a reason for closing it. You can close the wallet to disable access to the master key and prevent access to the encrypted columns.

Please advice what are the right procedure and normal way for implementing such features.