How to
Stop Digital Thieves with CGI by
Steve Humphrey, Visit
his website >>>
I'm going to
assume you're serious about your business. If you're not, I can't
help you anyway. You've gone as far as getting a real merchant account
to accept credit card payments online.
You know that
this was neither easy or cheap. So does everyone else! So, a merchant
account shows that you've made a serious commitment to your business.
That's good for customer confidence, which is good for business.
So far so good...
Now there's
the issue of selling stuff to people online. Your order form leads
them to feed their credit card info to a secure gateway, using software
you bought or leased from (or through) your merchant account provider.
Finally, the transaction is approved or denied.
If approved,
the software generates a receipt and emails you and the customer
each a copy. At this point, the customer is returned to a page you
specified. In the case of downloadable products, this is often the
page where they download your product. So, you've got the entire
process fully automated.
For a product
or service with a fairly low price point and a potential for many
thousands of sales, this seems ideal. You can quite literally make
sales and earn income 24 hours a day. So, what's the problem?
The form code
on your order page is the problem. If someone uses the ViewSource
function of their browser, they can see all your code. If they have
even a tiny bit of initiative and skill, they can locate the URL
of your download page. After all, it's right there in your form code!
CGI provides
two ways of fixing this problem. One involves using a script that
makes it impossible to view the source code. You can find a source
for such a script by searching the web. Expect to pay a lot for this
technology.
Another way
is to make the return path a script instead of the actual download
location. The script would be used to create and display the download
page. It would not be visible to the surfer, since it's not an HTML
document. The script can also record details of the transaction for
bookkeeping purposes.
I admit that
I discovered this by trial and error - and a lucky guess or two.
Your merchant account gateway software may have radically different
behavior than mine, but here's what I've learned:
The gateway
uses the POST method to send the customer to your specified return
URL (which can be a script as well as a web page). It also POSTs
most of its input data items at the same time. They are usually ignored,
but your script can read them if you want to!
Use the names
given to the form inputs. Have your script extract the values of
these "named parameters" at the time it creates the download page.
Record what you want to save about the transaction in your orders
file or database.
Now here's the
real secret to foiling the thieves. Inside the script, check to see
that the variables you extract contain non-empty values. Did you
get that?
Here's an example:
if ($email eq "") {exit;}
In this example,
the script expects to get an email address. If it contains no characters,
the script quits instantly. By testing for the presence of some data
in such fields as customer name, email address, item #, price, etc.,
you can tell whether the script was called after a successful transaction
- or by a thief...
Put all your
security checks prior to the code that creates the download page.
If any test fails, the script exits and the thief is left empty handed.
If your form-handling script can convert a product name to a product
ID that's never visible to a browser, this provides even more security.
This will be POSTed back to the script and you can check for it before
allowing the download.
Close these
security holes and you'll make more money. You may even sleep a little
better knowing that people can't steal that product you worked so
hard to create. I know I do!
Steve Humphrey
promises that you can learn to use CGI to turn your own website into
a marketing machine in two hours or less with his excellent CGI learning
system: "Learn to Use CGI in 2 Hours." He highly recommends this
book as required reading for anyone who wants to automate their website
or their marketing efforts. Click
here for immediate access.
top
of cgi scripts page
|