I am needing a prototype to be built for a mobile application allowing users to save their credit card details and addresses and then scanning a QR barcode in order to complete a transaction. I want the QR codes to be single use codes which are terminated as soon as the transaction is completed. I would also ask that users would be able to save more than one credit card on the application and be able to manage their spending on a separate page on the application. I would require a sign up page where details of the user are entered except for the 3 digits on the back of the card which will be used in order to verify their identity during transactions. I would also require a 4-digit alternating password to be entered upon starting the application. The QR codes would be displayed on either screens or paper receipts in order to be scanned.