Reformat MIFARE DESFire (MF3ICD40) NFC tags

Question

I have a few MIFARE DESFire (MF3ICD40) NFC cards that were once bus/train passes. I am trying to reformat the card. I do not care if I loose the information already on the card, or if I am only able to add more information to the card, if there is any free space. I am aware that there are apps that store commands within the app/cloud and just reads the NFC serial number, but I am looking to write these cards to be used by people other than just myself.

Click here for the NFC TagInfo by NXP's information on one of the cards.

Answer 1

You need to have the key of the master application in order to erase the memory or add further applications. Similarly, if you want to add files to the existing application (AppID 0x000001) you would need a key for that application.