Creating a certificate
For devices to interact, you need X.509 certificates. If don't have one, you can create a certificate, for example, with OpenSSL:
$ openssl req -x509 \ -newkey rsa:4096 \ -keyout key.pem \ -out cert.pem \ -nodes \ -days 365 \ -subj '/CN=localhost'
-x509: X.509 certificate.
newkey: Encryption algorithm.
-keyout: File to write the private key to.
-out: File to save the certificate to.
-nodes: This flag is set when no public key encryption is required.
-days: Certificate validity period in days.
-subj: Request object.