Sycurio Glossary.

Luhn Check (Luhn Algorithm)

Definition of Luhn Check

The Luhn Check, also known as the Luhn Algorithm, is a simple checksum formula used to validate various identification numbers, such as credit card numbers, IMEI numbers, and government-issued IDs. Developed by IBM scientist Hans Peter Luhn in 1954, this algorithm is widely employed to detect accidental errors in numeric sequences, ensuring their authenticity and integrity.

How the Luhn Algorithm Works

The Luhn Algorithm operates through the following steps:

  1. Starting from the rightmost digit, double the value of every second digit.
  2. If doubling a number results in a two-digit number, add the digits of the product together.
  3. Sum all the digits, including the unchanged digits from the original number.
  4. If the total modulo 10 is equal to 0, the number is valid according to the Luhn formula; otherwise, it is not valid.

For example, consider the credit card number 4 5 1 2 3 4 5 6 7 8 9 0 1 2 3 4. Applying the Luhn algorithm:

  • Double every second digit, starting from the right: 4 10 1 4 1 6 1 10 2 8 1 0 2 6 3 4.
  • Sum all the resulting digits: 4 + 1 + 1 + 4 + 1 + 6 + 1 + 1 + 0 + 2 + 8 + 1 + 0 + 2 + 6 + 3 + 4 = 55.
  • Since 55 is divisible by 10 without any remainder, the number is valid according to the Luhn algorithm.

Common Uses of the Luhn Check

The Luhn algorithm is utilized in various sectors to validate identification numbers:

  • Credit and Debit Cards: Major credit card providers like Visa, MasterCard, and American Express use the Luhn algorithm to validate card numbers before transactions.
  • IMEI Numbers: The International Mobile Equipment Identity (IMEI) numbers, used to identify mobile devices, utilize the Luhn algorithm.
  • Government Identification Numbers: Some national identification numbers, such as Canadian Social Insurance Numbers (SIN), employ the Luhn algorithm for validity checks.
  • Bank Account Numbers: Some countries use the Luhn algorithm to validate bank account numbers, ensuring the correctness of customer data during entry.
  • Utility Companies: Utility service providers often use the Luhn algorithm to validate customer account numbers, reducing billing errors and customer service issues.

Luhn Check Related Terms

  • Checksum: A value used to verify the integrity of a data set. The Luhn algorithm is a type of checksum formula.
  • Modulus 10 (Mod 10): Another name for the Luhn algorithm, referring to its use of modulo 10 arithmetic.
  • Validation Algorithm: A method used to check the validity of data, such as the Luhn algorithm for numeric identifiers.
  • Error Detection: The process of identifying and correcting errors in data, which the Luhn algorithm aids in by detecting common input errors.

The Luhn algorithm provides a quick and easy way to perform a basic validation check on identification numbers, including payment card numbers. It is commonly used in payment processing systems to help ensure the accuracy and integrity of entered card numbers before proceeding with transaction processing.

 
Back to Glossary