Hello I'm semi successfull at finally creating this algorithm and running it againts the variables I need to. But it doesn't seem to be a true HMAC-MD5 hash...
The successfull hash I create with an ASP script that works and plugs into my gateway looks like this... f81633aec015f23fbfd57bec77529c31
The one I create with the following code looks like this and has a trailing == in every one? JN4Kuk4KFN6pO/XA/wdAWg==