Is there an update to AuthorizeNet.php with SHA-512 to replace MD5 check?
Lesley, CiviCRM 5.11.0 doesn't use anymore MD5 check on authorize.net. This PR removes the check. However there is still not PR submitted by anyone to support SHA-512 check. 

If you can submit a PR to support this would be very useful to the community.

Cheers

Pradeep