Users can book a seat by logging in using an NFC reader. An Arduino board sends to the serial port the UID of the NFC tag (or smartphone).
The UID of a card can not be used as an unique identification for security related projects. Some Chinese cards allow to change the UID which means you can easily clone a card. For projects like access control, door opener or payment systems you must implement an additional security mechanism like a password or normal key.
However, for the sake of the presentation we used the UID both for the user id and for the key. Every time the RFID sensor reads a new card it sends to the Serial Port an 8 bytes buffer. The first 4 bytes are just 0xFF and they are needed to synchronize the transmitter and the receiver, then the last 4 bytes are the 4-bytes-long UID.
| 0xFF | 0xFF | 0xFF | 0xFF | uid[0] | uid[1] | uid[2] | uid[3] |
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