There are single custom user developed package which will having two customized function like encrypt and decrypt.
Four Simple steps to configure the PLSQL – DBMS_CRYPTO
1. You have to modify the EncryptionKey in this package inside encrypt function.
2. Wrapping the Package code completed and generate the sql file using Wrap Utility, (a standalone programming utility that encrypts PL/SQL source code)
3. Package source code is unreadable to anyone, even the owner of the package like DBA or Developer.
4. This way we can hide the encryption logic completely from every one.