Obscurity? Pffft. Simplicity! Nothing beats an HTML page right there in htdocs. You can store anything there and it's totally NoSQL as well. Anything else would be premature optimization. Do the simplest thing that could possibly work! Agile! I've got it all covered by unit tests so there can't be a problem. And if there's a breach I'll just rewrite it all in Haskell. Who are you anyway to tell a seasoned professional how to deal with credit card numbers securely? :)