This is an advanced approach into cracking the encryption keys.

Installed, because it has Mifare Classic DarkSide Key Recovery Tool.

The actual decryption work by the researchers was done on the widely deployed Mifare Classic wireless smartcard, now manufactured.

Hackers Find a Way to Crack Popular Smartcard in Minutes.

There are also other types like the “Mifare Classic 4k” and the “Mifare Mini” each having a different memory size. 1k stands for the size of data the tag can store. The NFC tag I analyzed is a so called “Mifare Classic 1k” tag.

You can also recharge your tag via the machine if you run out of credits. You can touch it with your tag to buy some drinks and the corresponding price is subtracted from the ammount stored on the tag. In this example the vending machine has an active NFC reader built in. This is usually used when sending data for example in “Android Beam”.

There is also an active - active mode where both endpoints can send data and need to be powered seperately. It also powers the passive device via an electromagnetic field. The active device scans for the passive one and establishes a connection on contact. Basically there is an active NFC enabled device (the reader) and a passive device (the tag). NFC nowadays is used for access cards, public transport, some more and in this case: Vending Machines. For more Infos on NFC you can read the Wikipedia article. NFC stands for Near Field Communication and is used to communicate over short distances. At the end I show you how to reprogram a vending machine’s NFC tag to contain more credits. In this blog post I will cover some quick basics about NFC, Mifare Classic and how to set up everything for reading and writing a NFC tag. Mifare Classic in general is stated insecure, because it’s encryption protocol has been cracked. The Proxmark is the tool behind all major RFID Security Research breakthroughs: Mifare Classic Crypto cracking, Mifare PRNG analysis, VingCard exploitation & defeat to name a few.

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