Updating Authorize.net in Magento for SHAW-512

1. Get a new Signature Key

You need to get a new Signature Key and add it to your Magento Admin configuration. 

1. Log into the Merchant Interface at https://account.authorize.net.
2. Click Account from the main toolbar.
3. Click Settings in the main left-side menu.
4. Click API Credentials & Keys.
5. Select New Signature Key. Review the options available.
6. Click Submit to continue.
7. Request and enter PIN for verification.
8. Your new Signature Key is displayed. Copy this key to add to your Magento Admin configuration.

2. Update your Magento Admin configuration

Take the following steps to update the Magento Admin configuration:

1. Log into the Magento Admin.

2. On the Admin sidebar, click Stores. Then under Settings, click Configuration.

3. In the panel, click Sales then Payment Methods.

4. Expand the Authorize.net Direct Post section.

5. In the Signature Key enter the SHA-512 Signature Key.

6. Click Save Config.