MCCI needs OpenSSL for a Windows project (that will be cross-platform). A casual search didn't turn up either a good source for cross-platform libraries, which meant we have to build them ourselves. A deeper search found a detailed guide here, and yet the details don't match what I found when I checked out the code; and the post doesn't talk about doing it directly from GitHub (which I wanted to do).
Here's the procedure for building OpenSSL on 64-bit Windows 10, with Visual Studio 2015. Others (July 2019) report that this procedure works with Visual Studio 2017 as well. I've not had a chance to try with Visual Studio 2019.
As this procedure dates from late 2016, you may find that there's a CMake or other, newer, procedure that's more suitable.
- If you don't have it, please install git bash from git-scm.com.