What is the option for winhttp to retrieve the server certificate ?

[afe]

What is the option for winhttp to retrieve the server certificate ? I want to determine whether a man-in-the-middle attack or proxy exists by retrieving the server certificate.

https://docs.microsoft.com/en-us/windows/win32/winhttp/ssl-in-winhttp

Although winhttp itself seems to have such an API, but I do not clear how to specify in AHK. Or is there any other simple way to determine whether the current connection is going through a proxy?