OpenSSL client certificates

[Doug Hardie]

I have a Lets Encrypt certificate my app uses for the clients to validate me.  However, I need to be able to validate the client's identity using a client certificate.  Lets Encrypt certificates can not be used to create client certificates.  So I need to be able to use a self-signed certificate for the client certificate validation.  I have been digging around through nginx code to see what I could find, but I am not sure it does that either.  Any ideas on how to do this with openssl?

-- Doug