iPhone
Apple Wallet
A store card with the balance as a currency field, so Wallet formats it in euros. The NFC payload is handed over encrypted via VAS.
Add the card
Android
Google Wallet
A gift card object through the Google Wallet API: the balance in euros, card number and update time, Smart Tap turned on.
What you get
Both cards for a made-up holder, drawn from the same data as the real ones. The pictures change every hour.
How it would work
Top up
A member pays cash or by transfer; the treasurer books it and the pass shows the new balance within seconds.
Tap
At the bar the reader takes the card ID from the phone. No PIN, no app, no cash box.
Book
The server deducts the drinks and pushes the balance. The cash book gets the line automatically.
Try it with your own reader
Elatec TWN4 firmware
The keyboard firmware for an Elatec TWN4 MultiTech reads this card too: hold it to the reader and it types the ID, followed by Enter. It is handed out on request only, because the image carries its key in plain form.
For an ACS WalletMate II there is a key package instead: it stores the demo key in the reader’s Apple slot, and the reader decrypts the pass itself. Both come through the same request.