IBM 3624 PIN Calculator

The IBM 3624 PIN calculation method is a standard used in banking systems to generate and verify PINs without storing the actual PIN values.

How IBM 3624 PIN Generation Works:

1. Natural PIN Generation: The system encrypts the PAN (card number) using a PIN Verification Key (PVK) with a DES or Triple DES algorithm.
2. Decimalization: The resulting ciphertext is converted to decimal digits using a decimalization table (a 16-character string mapping hexadecimal values to decimal).
3. PIN Extraction: The first N digits (typically 4) are extracted to form the Natural PIN.

PIN Offset:

The PIN offset is a value that allows verification of a customer-selected PIN without revealing the actual PIN:

1. Offset Calculation: When a customer selects a PIN, the system calculates the difference between the Natural PIN and the customer's PIN (digit by digit, modulo 10).
2. Storage: The offset is stored in the card or database, not the actual PIN.
3. Verification: To verify a PIN, the system recalculates the Natural PIN, applies the stored offset, and compares the result with the entered PIN.

Security Benefits:

• No PIN Storage: The actual PIN is never stored, only the offset.
• Key Protection: Security relies on protecting the PVK, not individual PINs.
• Customization: Allows customers to select their own PINs while maintaining security.