[ic] Credit card LUHN checking

[Corey Gilmore]

basically with credit cards you have 3 types of numbers.
your generic 16 (usually) number.
a valid (but not real) CC that passes the luhn check digit alg.
and then a *real* CC

If you take a 16 digit #, roughly every 9'th # will pass the luhn alg.
out of those, its totally random which of those ~1/9 #'s will be a REAL
CC.

If a card passes the luhn alg, it may, or may not be real.  if it fails
the alg, it cannot be real.

off topic, the first digit maps to a card type, the first 4-6 #'s map to
banks.

3=amex, 4=visa, 5=mc, 6=discover.
5490=mbna, etc.  i don't believe there is an offical (or legal) 'prefix'
mapping of cards->banks available to normal users.

.cfg


On Thu, 5 Jul 2001, Jonathan Clark wrote:

>
> > When placing trial orders in Interchange 4.6.5 (with a valid credit card
> > number) I receive following error message:
> >
> > Credit Card Information (Credit card number fails LUHN-10 check.)
> >
> > How do I disable this, as all credit card processing for the site will be
> > done manually.
>
> Why wouldn't you want LUHN-10 checking done?
>
> This ensures you don't have to process orders with bogus cc numbers and then
> contact the customer to get the correct number.
>
> To test use 4111 1111 1111 1111.
>
> Jonathan
> Webmaint.
>
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