Let's Encrypt Matrix
Let's Encrypt is a free Certificate Authority that makes it easy to secure your server's internet traffic. This makes it really easy to secure your Matrix homeserver, and this guide will explain exactly how you do this. Guide written by William A Stevens - thanks!
1: Get certificates
When executing the Let's Encrypt client, it will ask for the domain name of your server, and your email address. The domain list can include multiple names and should include any domain you want to access the server from.
Also, the certificates will be in a folder under /etc/letsencrypt (see below) and owned by root.
# certbot certonly --standalone
A note about renewal
These certificates will expire in 3 months. To renew certificates, run `certbot renew`. It is recommended to create a cronjob, which attempts renewal twice a day. Depending on your distribution, that could be already configured.
2: Install Certificates
At the top of your homeserver.yaml there should be two keys, `tls_certificate_path` and `tls_private_key_path`. These should be changed so that instead of pointing to the default keys, they now point to the Let's Encrypt keys. `tls_certificate_path` should point to `/etc/letsencrypt/live/(your domain name)/fullchain.pem`. `tls_private_key_path` should point to `/etc/letsencrypt/live/(your domain name)/privkey.pem`. `tls_dh_params_path` can stay the same as before.