HTTPS for dl-cdn.alpinelinux.org
It would provide more security and increase adoption if packages and releases were served over HTTPS.
https://letsencrypt.org provides free certificates. https://certbot.eff.org. is the tool that manages the certificate acquiring process. You can use a plugin for nginx to automatically verify the domain, or you can just run a script that will either serve a file, or create a standalone webserver temporarily for verification. They also have plugins for Apache, HAProxy, etc.
(from redmine: issue id 7768, created on 2017-08-26, closed on 2018-01-25)