E-xact Knowledge Base

There are indeed 3 different hash values or calculations - we'll break it down:

x_fp_hash: this value validates that the merchant’s server generated the redirect parameters correctly. This serves solely as verification to E-xact that the form was generated by the merchant's server, and not by the customer or a third party.

x_MD5_hash: (aka the Relay Response Signature) this parameter is specific to the Relay Response method. When E-xact sends the transaction results to the merchant we'll sign it with a cryptographic hash - the x_MD5_hash - that the merchant uses to solely to verify that the message is coming from E-xact.

Relay Response Key: this parameter is also specific to the Relay Response method. It is generated in the merchant in the Hosted Checkout Administrative Console in RPM. This hash key is one of the values used to calculate the x_MD5_hash.