If you receive error messages like;
ORA-28817: PL/SQL function returned an error.
ORA-06512: at “SYS.DBMS_CRYPTO_FFI”, line XXX.
ORA-06512: at “SYS.DBMS_CRYPTO”, line XX .. etc.
Then, check these conditions;
* the encryption key and encryption type must be the same as while encrption/decryption
*the character set used by Oracle and your machine must be overlapped
*the data that you are decrypting is NOT the same as the one encrypted
