Authorize.Net: support ending for MD5
Authorize.net will stop supporting MD5 based hash usage on March 14.
Magento implements the Authorize.Net Direct Post payment method, using Authorize.Net's AIM (Advanced Integration Method) and DPM (Direct Post method) APIs, which use MD5 based hash. Authorize.Net will stop supporting MD5 based hash tag on March 14.
This issue affects all Magento versions, Magento 1, Magento 2, Magento Commerce, Magento Commerce Cloud and Open Source.
Users of Authorize.Net must do the following to avoid any interruption to their payment service.
Apply Patch provided by Magento
Replace existing MD5 hash with a Signature Key (SHA-512) in the Magento Admin configuration settings.
The Magento patch was released on March 1, and instructions can be found on the Magento Help Centre.