If you attended WHY2025, you were given an "WHY2025 Payment Card", a Mifare Ultralight AES NFC-card.

For usage during the event, a variety of security features have been enabled on the cards, such as: Random ID, CMAC-protected communication and per-card AES keys.

Using this app, you can format/wipe your card back to factory condition and use it for whatever you want - no need to throw away a perfectly good RFID-card!

Please note that formatting the card will only be made possible after WHY2025 concludes (after August, 12th 2025).