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What would be the equivalent of below s_server command in stunnel?

openssl s_server -accept 5003 -engine chil -keyform engine -key rsa-priv -cert public.pem -tls1_2

In this example "rsa-priv" references the private key inside a hardware security module, not a pem file.

I saw an option for engineid in the documentation, but nothing for keyform parameter.