Which encryption method is the best?

Hello All,

 

I have a table T1, and need to encrypt 2 columns in that table, say Col1 and Col2. The table has a total of 10 columns. The value of the two columns to be encrypted are confidential.

Which is the best way to encrypt the columns??

1. Using column Masking - by using dbms_rls

2. Dbms_Crypto package

3. Transparent Data Encryption

What are the pros and cons of the above 3 approaches??

Thanks in advance!