Any body have an idea about this ... !! What can we do in Magento 1.9.x versions.
Authorize developer refferaral url
Authorize.Net is phasing out the MD5 based transHash element in favor of the SHA-512 based transHashSHA2. The setting in the Merchant Interface which controls the MD5 Hash option will be removed by the end of January 2019, and the transHash element will stop returning values at a later date to be determined.
Thanks in advance