Integrating With Authorize.net Using SIM

By Will Bontrager
2003-02-11

Using SSI To Insert the Fingerprint

Note: Using a "get" URL in the context presented in this
section might be less secure than the methods described
in the "Modifying Scripts To Create the Fingerprint"
and "Detailed Instructions For Master Form" sections,
below. I don't know this for a fact, but it seems to me
that providing a URL to obtain the fingerprint for a
specific order amount could be a security consideration.

If you know the total amount of the transaction at the time the order verification form is to be displayed to your customer, you might use SSI to insert the fingerprint. SSI can be used in either of two situations:

1. When you have only one product at one price, script
SIM.cgi (included with the SIM.zip file) can be
customized to always use that transaction amount
when generating the fingerprint. An SSI tag calls
SIM.cgi.

2. When you're able to calculate the total amount of
the transaction and send the customer's browser to
the order verification form as a "get" URL with a
value representing the total amount, then the SSI
that calls SIM.cgi can extract the value from the
URL and use that transaction amount when generating
the fingerprint. Example "get" URL with a value:

http://domain.com/orderverification.shtml?24.95

In the above URL, 24.95 would be used as the amount
when generating the fingerprint.

JavaScript might be used to calculate the amount
and store it in a variable named "total", for
example. Then the following line could give the
browser a "get" URL with a value:

window.location='http://domain.com/orderverification.shtml' +
'?' +
total;

If you want to specify a currency code, append an
ampersand and the currency code to the "get" URL.
Example:

http://domain.com/orderverification.shtml?24.95&USD

Methods other than JavaScript can be used to
calculate the total amount. So long as the browser
can be sent to the order verification form using a
"get" URL with the total amount as the value, an
SSI tag can call SIM.cgi to insert the fingerprint.

An example order verification form using SSI to insert the fingerprint is included in SIM.zip as file SIMexample_SSI.shtml

Tutorial Pages:
» Integrating With Authorize.net Using SIM
» How SIM Works
» The Order Verification Form
» Customizing the SIM.cgi Script
» Using SSI To Insert the Fingerprint
» Using JavaScript To Insert the Fingerprint
» Using a Perl Program To Display the Form With Fingerprint Automatically Inserted
» Modifying Scripts To Create the Fingerprint
» Detailed Instructions For Master Form
» The Order Verification Form Modification Step
» Uploading the Three Files To Your Server
» Testing
» Changing Transaction Keys

Copyright 2004 Bontrager Connection, LLC

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