Created this module for a client of ours as they were using the Authorize.Net Server Integration Method (SIM) module and I couldn't find any module for it among Ãœbercart's contribs.
Anyway, from the site:
==
SIM uses scripting techniques to authenticate transactions with a unique transaction fingerprint. SIM provides a customizable, secure hosted payment form to make integration easy for Web merchants that do not have an SSL certificate. The Authorize.Net Payment Gateway can handle all the steps in the secure transaction process — payment data collection, data submission and the response to the customer — while keeping Authorize.Net virtually transparent. View this guide.
* Payment gateway hosted payment form employs 128-bit SSL data encryption.
* Digital fingerprints enhance security, providing multiple layers of authentication.
* Customize the look and feel of the payment gateway hosted payment form and/or receipt page.
==
Like the AIM module, there are 3 transaction modes :
- Production - which connects to https://secure.authorize.net/gateway/transact.dll with x_test_request set to false
- Live-test - which connects to https://secure.authorize.net/gateway/transact.dll with x_test_request set to true
- Test - which connects to https://test.authorize.net/gateway/transact.dll with x_test_request set to true
Settings also include:
- Login
- Transaction Key
- Currency Code
- FDS
- Transaction Type
- Logo URL (for the Authorize.net page)
- Background URL (for the Authorize.net page)
- Link Text (for the redirect back button)
To install, just download and extract into the /ubercart/payment directory.
NOTE: so far, this has been tested with the in Test mode. Waiting for my client to give me the go signal to test with the 2 other modes.
NOTE [20080611] : this has been tested on the production and live test modes already. both worked. 
-- sarah (woohoo! first attempt at a module.)
Development
| Preview | Attachment | Size |
|---|---|---|
| uc_authorizenet_sim.tar.gz | 91.36 KB |
Two problems I found implementing this module, that I was able to fix.
line 300 users hash_hmac which is only in php 5. If you're running php4 you can add this function
function hmac ($key, $data){
return (bin2hex (mhash(MHASH_MD5, $data, $key)));
}
and then use $fingerprint = hmac($txn_key, $login . "^" . $sequence . "^" . $tstamp . "^" . $amount . "^" . $ccode);
instead of $fingerprint = hash_hmac('md5', $login . "^" . $sequence . "^" . $tstamp . "^" . $amount . "^" . $ccode, $txn_key);
Second problem is that the amount wasn't formatted correctly so authnet was rejecting it, so to fix that underneath
$amount = $order->order_total;
I added:
$amount = uc_currency_format($amount, FALSE, FALSE, '.');