Weighing Down "The Unbearable Lightness of PIN Cracking" (Extended Version)

Responding to the PIN cracking attacks from Berkman and Ostrovsky (FC 2007), the authors outline a simple solution called salted-PIN. A randomly generated salt value of adequate length (e.g. 128-bit) is stored on a bank card in plaintext, and in an encrypted form at a verification facility under a bank-chosen salt key. Instead of sending the regular user PIN, salted-PIN requires an ATM to generate a Transport Final PIN from a user PIN, account number, and the salt value (stored on the bank card) through, e.g., a pseudo-random function. They explore different attacks on this solution, and propose three variants of salted-PIN that can protect against known attacks.