I got this message when running in a VMWare environment or by using crappy hardware.At the end I show you how to reprogram a vending machines NFC tag to contain more credits.
NFC nowadays is used for access cards, public transport, some more and in this case: Vending Machines. Basically there is an active NFC enabled device (the reader) and a passive device (the tag). The active device scans for the passive one and establishes a connection on contact. It also powers the passive device via an electromagnetic field. There is also an active - active mode where both endpoints can send data and need to be powered seperately. This is usually used when sending data for example in Android Beam. You can touch it with your tag to buy some drinks and the corresponding price is subtracted from the ammount stored on the tag. You can also recharge your tag via the machine if you run out of credits. ![]() More deatiled Information about this can be found in the following links. Each of these sectors has 3 blocks of data storage and 1 block for storing the secret access keys and access controls. Before reading a sector, the reader must authenticate to the tag with a secret access key. As an example you can define to use Key A for reading the block and Key B for writing to it. Sector 0 Block 0 also contains a non changeable UID (the tags unique ID) and some manufacturer data. This section is only writeable on some special chinese tags. For more information on Mifare 1k Tags, the memory layout and more details you can visit these pages. ![]() Mifare Classic Universal Toolkit Apk Drivers Mess WithConnecting a NFC device to a VM running linux will not work reliable because the drivers mess with this timing. I spent a lot of time finding this out, so please boot into a linux live cd for the following example or use a Raspberry Pi. You can overwrite the Kali installation with the setup from above. Mifare Classic Universal Toolkit Apk Offline Cracker AvailableWe will use the tool mfoc - Mifare Classic Offline Cracker available from. On my sample tag the whole procedure was done in under one minute.
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