The Unbearable Lightness of PIN Cracking

Responding to the PIN cracking attacks from Berkman and Ostrovsky (FC 2007), we 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. We explore different attacks on this solution, and propose three variants of salted-PIN that can protect against known attacks. Depending on the solution variation, attacks at a malicious intermediate switch now may only reveal the Transport Final PIN; both the user PIN and salt value remain beyond the reach of an attacker’s switch. Salted-PIN requires modifications to service points (e.g. ATM, point-of-sale), issuer/verification facilities, and bank cards;...

• Type: Conference
• Year: 2007
• Where: FC
• Authors: Omer Berkman, Odelia Moshe Ostrovsky
• Keywords: FC 2007, Salt Value, Transport Final PIN, User Pin