Create Root Certificate Authority and self-signed certificate for your Home Assistant. Compatible with Chrome browser > version 58, including the macOS Catalina 10.15 / iOS 13 (and above) new requirements.
Attention: this is the key used to sign the certificate requests, anyone holding this can sign certificates on your behalf. So keep it in a safe place!
openssl genrsa -des3 -out rootCA.key 4096