SQL & PL/SQL :: How To Create Hidden Column In Table

I want to create a column which will be having unique values but while selecting data from table i am not willing to display same column in output.

SQL> create table temp
2 (
3 c1 number,
4 c2 number,
5 c3 number
6 );

Table created.

SQL> insert into temp values (1,2,3);

1 row created.

SQL> select * from temp;

C1 C2 C3
---------- ---------- ----------
1 2

I want C3 as a hidden column and while selecting like

select * from temp;
expected output is...

C1 C2
---------- ----------
1 2

My main target is, C3 column should not display in select * ... stm but column with data should be there in table.