Quote:
Originally Posted by quantum-x
The first four digits of a CC are simply the bank identifiers. If you have a user's laster 12 digits, and GeoIP their country, run that against a list of card-issuing banks in that country (normally going to be 10 or less) - bam!
If you're really looking to verify cc#s, check out http://en.wikipedia.org/wiki/Luhn_algorithm
Note for advanced players: the linked PHP version on that article has some bugs in it. |
i know the algorithm for that, but here you can check if the card has been used on a pornsite so you really know its valid ( its just an extra chck )