We've just released a major update for the Authorize.net gateway for SimpleCart. Contrary to an earlier assessment a few months ago which led me to believe no update was necessary, this weekend it became clear that the SimpleCart Authorize.net implementation was affected by the MD5 hash deprecation that you may have read about. As a result, payments via Authorize.net will have thrown an error in the last two weeks.
To remedy that, version 2.0 of the Authorize.net gateway for SimpleCart is now available, plus a complementary SimpleCart 2.6.2 release that incorporates some additional default styles.
The key functionality of 2.0 is that it actually works, but we also replaced the legacy SIM implementation (using a relay response) with the newer Accept.js implementation. That means your customers stay on the site, no more redirects, improving the usability of your checkout.
When upgrading, you'll need to update the gateway properties with your client key, after that it's pretty much plug and play assuming you've used the standard checkout templates. Please see the documentation for additional information. If you run into any issues upgrading to 2.0, or have any questions, please email [email protected]
This does not affect the Commerce implementation of Authorize.net, which already uses Accept.js, though we will have some more gateway updates for Commerce in a few weeks as well.