I'm missing something. I used your Create Self-Signed SSL Certificate tool, plugged the resulting cert.pem file and the privatekey.pem files into this tool, and am told they do not match. Should this not just work, or am I just dumb tonight?

Figured out my problem from almost two years ago. If I specify a passphrase for my certificate, then your tool never matches. Perhaps you could add a field for an optional passphrase?