In this blog I explain the numerous ways to identify and validate a credit card number (CCN). The main point in this posting is to articulate the complex nature of identifying sensitive data. The complexities of identifying these types of sensitive data manually are not practical thus the need to automate using tools such as "Spirion.com".
Below are techniques that can be used to perform cursory checks on CCN's and an explanation of each of the most common validation techniques.
The Luhn Algorithm is a simple checksum formula used to validate a variety of identification numbers, such as credit card numbers and numerous others such as:
In addition most credit cards and government identification numbers use this algorithm as a simple method of distinguishing valid numbers from mistyped or otherwise incorrect numbers.
The first digit of a credit card number represents the category of entity which issued the card.
The first six digits of a card number identify the institution that issued the card to the card holder.
Digits 7 to final number minus 1 (the last is the checksum) indicate the individual account identifier.