oracle provide wrap utility and DBMS_DDL.WRAP Function to encrypt pl/sql code. its not possible to unwrap again. but on following site its easily possible just paste the encrypted code and u got unwrap code on only one click http://www.codecrete.net/UnwrapIt/ please tell me if any one have any other option or method for encrypt ps/sql code.
I don't know any supported alternatives to the WRAP utility (or DBMS_DDL.WRAP).
Wrapping code prevents the casual observer, but as you've seen, people have worked out ways to unwrap code. This is always going to be possible because the database has to be able to understand the contents of the code, so it must be able to unwrap it internally. Oracle have changed the wrapping algorithm several times. Each time it has been cracked. This situation is that same as decompiling Java or C code. I think you just have to live with it.
Assuming you are controlling the servers, you can prevent access to the wrapped source. If they don't have the wrapped code, they can't unwrap it. :)