Millions of NFC Mifare Classic cards are used for public transport, access control and other purposes. These NFC tags use encryption so that the data on NFC tag cannot be read or changed by someone who scans the tag without the applicable key.
Based on my information the authorized read/write devices transmit a secret key when the nfc tag is in rage. This triggers the micro controller inside the nfc tag to use the secret key and permit the read/write device to read or change tag's data. Is it possible to capture the secret key transmitted from the read/write device by emulating an NFC card or by special software and record the key?
I read somewhere that this secret key is transmitted to NFC tag as plain text, can you tell me if I this is right?