MFC Balance

Generic Reader for Balance on MIFARE Classic Cards

Installation

Or

1. Download the latest APK from the release section
2. Run downloaded apk-file
3. You may get asked if you want to install this app from an unknown source

FAQ

How can I find the correct settings values (eg. Sector Number)?

1. Get the MIFARE Classic Tool app.
2. Using this app, read out your card and save it as a dump.
3. Now buy something using the card or recharge it with some money (do anything that changes your balance).
4. After that, create a second dump. Using TOOLS > Diff Tool, compare those two dumps.
5. If nothing changed at all, I'm sorry, but you cannot use this app with this card (there is just no way).
6. If something (maybe even a lot) changed on the card, you now have to fiddle around a bit. Convert you current balance (without any decimal points) to hexadecimal (eg. 34.87 -> 3487 -> 0D9F or by swapping groups of two ("Little-Endian"): 9F0D) and try to find that number within the areas that changed.
7. If you found a group of bytes that match your current balance, read off the position of this number (Sector, Block, etc.) within the MIFARE Classic Tool app. The Byte Offset in Block is how many bytes ("groups of two") the number is from the left, starting at 0. The Number Size specifies how many bytes ("groups of two") the number is long.
8. Enter these values into the Settings page of the MFC Balance app and try it out! If it doesn't work, or you get weird numbers, try using the Debug Mode to see at which point the reading process is going south.

Where can I get the key to my card?

Depending on your country's legislation, cracking a key (or even just using a cracked key) could be illegal. That said, if you know your way around some tech stuffs, one could use tools like Flipper Zero or Proxmark to extract the key from an NFC card. There are enough tutorials online, so I won't be going into details here. There are also many lists of commonly used MIFARE Classic keys on the internet. You may try your luck with those first.

If the type of card you want to use the app with is used by a lot of people (possibly even some IT nerds), you could try asking around. At many places, the card keys are open secrets.

Attribution / Credits

• Compose Preference (Apache License 2.0): https://github.com/zhanghai/ComposePreference