Help:Encryption Keys - metrodroid/metrodroid GitHub Wiki

Some NFC smartcards require encryption keys to read useful data. They are labelled with a warning in Metrodroid's "Supported Cards" screen:

"Encryption keys are required to read this card."

"Des clés de chiffrement sont requises pour lire cette carte."

「このカードを読み取るために、暗号化鍵が必要です。」

"Er zijn ontsleutelingssleutels benodigd om deze kaart uit te kunnen lezen."

"Krypteringsnøkler kreves for å lese dette kortet."

When you try to scan a card that needs encryption keys, you will get an error message.

Metrodroid only includes a few "default" keys for cards.

Most transit agencies use a key diversification function for all parts of the card. This means that each card will have a unique encryption key that is used to access it. There is no "one key" which will unlock every card.

Some cards have security weaknesses which permit cracking of the card's encryption key. You will need special hardware in order to do this. It is not possible to crack a card using your phone's in-built NFC hardware.

See Cracking keys for more tips on software and hardware which may be used to crack keys. I can't give email support about this process either, or do a crack-by-mail service.