If you use ClickBank to sell products, this is for you. Use it, and you'll have reason for less worries about security.

The article presents a script you can use to authenticate ClickBank purchases. It uses the CGI purchase validation method which ClickBank notes is "for experienced programmers only."

Well, with the Advanced ClickBank Authentication CGI program, you don't have to be an experienced programmer. Just decide on a Secret Key, type the Secret Key in both the script and in the ClickBank control panel, make a simple change to your purchase links, and you're good to go. Everything is explained here.

The program is free to readers for the week this article is in syndication, ending December 4, 2001. See URL http://willmaster.com/a/12/pl.pl?acba to get it. Advanced ClickBank Authentication retails for $25 (USD).

Note 1: If you would rather not deal with a Secret Key or security isn't a high priority, the Simple ClickBank Authentication CGI program, presented in an article several weeks ago, may be ideal for you. It verifies that the ClickBank receipt number is in a valid format and verifies that the customer arrived at your "thankyou" page from a ClickBank URL. See http://willmaster.com/a/12/pl.pl?acbaart

Note 2: If you sell downloadable products and don't use ClickBank, see http://willmaster.com/a/12/pl.pl?cbnkmerchant for more information.

The Advanced ClickBank Authentication CGI program is easy to implement. Just follow these steps:

Step One —

Obtain the program from http://willmaster.com/a/12/pl.pl?acba

When you decompress the ZIP file, you'll find:

1. The script, acb.cgi

2. An example "order okay" template page, cbthanks.html

3. An example "authentication failed" template page, cbfailed.html

4. The license agreement, LicenseAgreement.html, which you'll need to read and agree to before installing or using Advanced ClickBank Authentication.

If you modify either/both of the above templates, put the code

[[cbreceipt]]

wherever you want the script to insert the ClickBank receipt number. Also, if you include any images, sounds, or other page elements that require a URL, use the complete http://... URL instead of a relative URL.

Step Two —

Near the top of the script are three places to customize. Put your custom data inside the apostrophes of the lines indicated.

(Use a plain text word processor like NotePad or BBEdit to customize the script.)

The first place to customize is where you specify your Secret Key. The Secret Key can be up to 16 characters long and must be composed only of letters and/or numbers. In a later step, you'll also put this same Secret Key into your ClickBank control panel.

The other two places are where you specify (1) the file name of the web page template to present when authentication passes and (2) the file name of the web page template to present if authentication fails.

Finally, verify that the first line of the script points to the location of perl on your server.

Upload the script *as plain text* along with the two web page templates (see file list at Step One) to your server into a directory that is allowed to run Perl CGI programs. Once there, set global execute permissions, 0755, for the script. The web page templates do not need special permissions.

The URL of the script you just uploaded will be the URL of the "thank you page" for your product sale. In a later step, you will specify this URL in your ClickBank control panel.

If installation goes awry, http://mastercgi.com/faq/ has a nice list of fixes for different types of errors.

Step Three —

Go to your ClickBank control panel, the "Modify Account" page where you type in your "thank you page" URLs and set your product prices.

1. Type the the URL of the script you uploaded in Step Two as the "thank you page" for your product.

   (If you sell more than one product, you may need to install more than one copy of the script, each with a different file name.)

2. Type the Secret Key in the form field provided for it. The Secret Key must be exactly the same as you specified in the script at Step Two.

Step Four —

The ClickBank link on your product page, the sales link that takes people to ClickBank to pay for their order, must be modified a little.

The sales link needs a seed, a unique string of letters and/or numbers, for ClickBank to use when calculating a verification code. The seed can be anything, so long as it is not the same as your Secret Key. The ClickBank site does not mention a minimum or maximum number of characters for the seed, but three to 10 characters should do just fine. (If you have more than one product link, use a different seed for each link.)

Now that you've decided what your seed will be, we'll modify the sales link.

As an example, let's assume this is your existing sales link:

http://www.clickbank.net/sell.cgi?Code/1/Item

In the above, "Code/1/Item" would be your normal link code.

The following link contains underscores where new information will be put:

http://www.clickbank.net/sell.cgi?_____Code/1/Item_____

Replace the first underscore with: link=

Replace the second underscore with: &seed=XYZ (where XYZ represents the seed you're using)

The new sales link would then be:

http://www.clickbank.net/sell.cgi?link=Code/1/Item&seed=XYZ

Step Five —

Test.

In the ClickBank control panel, make a test product entry with $0.00 sale price. Then, make a page with a sales link for that product entry.

Once the test works to your satisfaction, go live and make a lot of money.

By: Will Bontrager

Copyright 2001 Bontrager Connection, LLC
http://willmaster.com/possibilities/
subscribe-possibilities@willmaster.com