svenikea

First we need to obtain a certificate

Generate an RSA private key

openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:keysize -out file

If an encrypted key is desired, use the -aes-256-cbc option.

Generate a certificate signing request

openssl req -new -sha256 -key private_key -out filename

Generate a self-signed certificate

openssl req -key private_key -x509 -new -days days -out filename