PayPal IPN to SHA-256 Notification

Hello,

I received an urgent notification from PayPal stating they are getting rid of the IPN and using SHA-256. I am using an older modified version of Opencart that uses IPN. Is there something that needs to be changed with my version so this does not disrupt my service? Please advise. Thank you!

I did find this http://forum.opencart.com/viewtopic.php?f=179&t=151599