Micro Payment
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The Micro Payment Application “NFC Wallet” consists out of four different parts. The first one - and the only one that is actually recognized by the user – is the J2ME Applications running on the device. This part provides the user with a nice GUI and allows him/her to recharge the wallet over the air and view the amount of money available on the handset. To recharge the wallet, the J2ME application is able to establish a GPRS connection to a transaction server located at the mobile network operator´s bank, the A1-Bank.
The transaction server accepts the incoming connection from the NFC handset. The authentication of the device is done thru a solution of the mobile network operator called dataguard. The server checks the balance of the account of the customer and then sends the money (encrypted) back to the handset. There the money is directly stored in the secure element.
The data connection itself is secured thru AES encryption. The encryption for the request made from the handset and the response sent by the server is done by a JCOP application that also is holding the keys in order to provide a sound security for the system. The money itself is not stored in the JCOP application but in the Mifare section. This is necessary as the mobile phone must be able to communicate with an already existing legacy infrastructure. Actually vending machines for this NFC trial have been specially adopted to provide a better consumer usability.
The fourth part of the system is a web interface, that allows the user to see the balance of his account, when money are recharged and when money was spent.