One thing to be careful of is that NXP now sells āMifare Classic 1kā cards that are not the same old chip versionā¦ they look exactly the same, but the crypto-1 key cracking problem has been solved on these. Sometimes they are called Mifare S50 EV1 chips, but basically they are not vulnerable to cracking like the original mifare S50 1k chips areā¦ it might be that you do have one of these newer chips in your desired source card. If possible, can you try reading your source card with TagInfo on an Android phone that supports reading non-NFC compliant Mifare cards and posting the info screens here?