Recently we used Drupal Content Management System for one of the Website and now the next concern is to make our website and implementation as secure as possible. Files have to be made secure first and than the data in the database. I am applying proper security permissions to all my files and folders but i am yet to make the database secure specially one field which has some credit cards of this website users. Now tell me how to make a column in a database can be made secure and what security module in Drupal must i use to this task.