CVV numbers

Sat Jun 9 14:14:42 UTC 2012

On 6/9/2012 12:06 AM, Hal Murray wrote:
>
> In response to my comment about:
>
>> If I'm not supposed to not "tell anyone", why is it even printed where I can
>> read it?
>
> (Sorry for the extra not in there.)

The CVV number is simply to prove that the card is in your possession. 
The percentage of the sale that goes to Amex/Visa/Mastercard/Discover 
(etc) is determined by whether the merchant can supply various items, 
and the CVV is one of them. Running the card physically (where the 
merchant touches your card, and presumably verifies that you are you) 
gets taxed the lowest. The CVV is just meant to replace that 
verification. Sort of. I disapprove *strongly* of any online merchant 
that does not request this simple item, but it's not magic.

> I got an off list suggestion of:
>    http://www.cvvnumber.com/
>
> It looks reasonable.
>
> But then, whois for cvvnumber.com says:

> Registrant:
>     Domains By Proxy, LLC

> Should I really take them seriously?

No. No you should not. Here's the canonical Wikipedia entry, for those 
still playing along.

http://en.wikipedia.org/wiki/Luhn_algorithm

There's a few more grown-up words there. The best part is that it's a 
public algorithm. What's not to like?

-- 
A picture is worth 10K words -- but only those to describe
the picture.  Hardly any sets of 10K words can be adequately
described with pictures.