What is the Luhn Algorithm?
The Luhn algorithm, also known as the Luhn formula, is a simple checksum formula used to validate a variety of identification numbers, most notably credit card numbers. It is designed to protect against accidental errors, such as a mistyped digit, but not against intentional fraud.
How to Use the Luhn Algorithm for CVV Validation
Start by reversing the digits of the number you want to validate.
Double every second digit from the right (this is the second, fourth, sixth, etc., digits, counting from the right).
If doubling of a digit results in a number greater than 9, subtract 9 from the result.
Sum all the digits.
If the total modulo 10 is equal to 0, then the number is valid according to the Luhn formula; otherwise, it is not valid.
Why is CVV Validation Important?
CVV (Card Verification Value) is a three or four-digit number printed on the back of a credit card. It is used by merchants to verify the identity of the cardholder during transactions. By using the Luhn algorithm to validate the CVV, you can help prevent fraudulent transactions.