C# Recover Windows 8 And Server 2012 CD key

My company has recently been request by Microsoft for an audit. All of the IT staff is new to the company, myself included. But the issue is, we don't know what all the keys are on our network or where they came from, and with absolutely no documentation. We have about as many physicals as virtual machines for our servers, around 80, plus another 80 or so desktops on the floor.

With the background out of the way I do have quite a bit of programming experience in C#. I've been searching around for some code to recover the CD keys of windows 8/8.1 and server 2012/2012 R2 but all the code I have found only works for Windows 7/Server 2008 R2 and lower. I have compiled and tested may forms of code and compared them against Nirsoft ProduKey and only Nirsoft has been able to give me a valid key.

I'm looking for a code snippet that will decode Windows 8/Server 2012 CD Keys. Any help or insight would be much appreciated.

Thanks