Where does GitHub for Windows keep its SSH key?

It's in %HOMEDRIVE%%HOMEPATH%\.ssh.

Note that GitHub for Windows normally uses SSL; SSH keys won't have been created unless you've used an SSH repository with it at some point.

%HOMEDRIVE%%HOMEPATH%\.ssh\id_rsa.pub is where the key is.

The default location is: %HOMEDRIVE%%HOMEPATH%\.ssh\id_rsa.pub. That would expand to something like C:\Users\dennis\.ssh\id_rsa.pub.

If %HOMEDRIVE%%HOMEPATH%\.ssh\id_rsa.pub already exists, GitHub creates a key named github_rsa(.pub) in the same folder.

On my work PC it is in %USERPROFILE%/.ssh/ and not %HOMEDRIVE%%HOMEPATH%/.ssh/.

On many computers those folders are the same location, but it depends on the configuration. So it seems %USERPROFILE% is the location used by GitHub for Windows, which is also the ~ home location for its Git Bash.

This is confusing since my Windows Git default installation uses %HOMEDRIVE%%HOMEPATH% as its ~ home location.