Setting up Web Key Directory (WKD) for Proton Mail using Cloudflare Workers

Proton Mail WDK on CF Workers.md

Web Key Directory for Proton Mail using Cloudflare Workers

Web Key Directory is a way for non-Proton users find your keys and encrypt the messages sent to you. Proton doesn't offer this for custom domains out-of-the-box, but you can proxy requests from your domain to Proton.

1. Create a Cloudflare Worker
2. Put this code in the Worker:

export default {
  async fetch(request, env, ctx) {
    var url = new URL(request.url);

    if (!url.pathname.startsWith("/.well-known/openpgpkey/"))
      return new Response("Path not found", { status: 404 });    

    url.hostname = "api.protonmail.ch";
    return fetch(url.toString(), request);
  },
};

3. Save and assign it to openpgpkey.mydomain.com and you're done.