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Yes, this is exactly what a message authentication code is for. Its job is to prevent an attacker from tampering with your message, or from forging completely bogus messages. For a secure MAC, it should not matter what these messages contain. (And no, a secure MAC cannot compromise your key; if it did, it would by definition not be secure, since an ...


1

BDK and KSN are used to derive a transaction key which is unique for that session. The are unique because KSN is updated after each transaction. Once this key is derived you apply different variants to get PIN, Data or MAC key. For the PIN and MAC key: these variants are simply XORed with derived key. One more encryption is performed to calculate the data ...



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