Understanding and Implementing the Luhn Algorithm

Photo by blocks on Unsplash

The Luhn algorithm, also known as the “modulus 10” or “mod 10” algorithm, is a simple checksum formula used to validate various identification numbers. Developed by IBM scientist Hans Peter Luhn in 1954, it is primarily designed to protect against accidental errors such as mistyping or altering digits. The algorithm is not a cryptographic hash function but a straightforward and effective way to detect common mistakes in sequences of numbers.

Where is the Luhn Algorithm Used?

The Luhn algorithm is widely used in various industries to validate identification numbers. Some common applications include:

• Credit Card Numbers: Major credit card companies like Visa, MasterCard, and American Express use the Luhn algorithm to verify the validity of a card number.
• IMEI Numbers: The International Mobile Equipment Identity (IMEI) numbers used to identify mobile devices are validated using the Luhn algorithm.
• National Identification Numbers: In some countries, national ID numbers, social security numbers, and similar identifiers are validated using this algorithm.
• Bank Account Numbers: Certain banking systems employ the Luhn algorithm to check the validity of account numbers.

What Kinds of Numbers…