Hello, I have a situation where I need a character field displayed on a xml view, but I dont want the value stored in the DB for security reasons

I am making a module that uses authorize.net so I need the user to enter the credit card info so that it can be processed, but I do not want to save the credit card info on the table.

Is there a way to not store character fields in the db?

I cant use a function field because its not editable, so I need a character field so that the user can enter the credit card info on the form and submit it.