Basic Access Authentication With Cloudflare Workers

Basic access authentication is a method for enforcing access controls to resources on the World Wide Web. For authorization a client needs to provide an Authorization header with an authentication method Basic and credentials encoded as Base64, I.e. Basic username:password. On unauthorized requests the server should return a response whose header contains a HTTP 401 Unauthorized status, and a WWW-Authenticate field with method Basic (see Wikipedia).

Caution. Basic access authentication just encodes the transmitted credentials, to add confidentiality a secure transportation protocol like TLS(HTTPS) is required.

Cloudflare workers implement the Service Worker API, therefore it’s straight forward to implement basic access authentication in JavaScript.

const authorization = "Basic dXNlcm5hbWU6cGFzc3dvcmQ=";

const handle = async function (request) {
  if (request.headers.get("Authorization") !== authorization) {
    return new Response(null, {
      status: "401",
      statusDescription: "Unauthorized",
      body: "Unauthorized",
      headers: {
        "WWW-Authenticate": "Basic",
      },
    });
  }

  return await fetch(request);
};

addEventListener("fetch", function (event) {
  event.respondWith(handle(event.request));
});

The authorization string from the preceding snippet can be generated as follows.

printf "Basic %s\n" $(printf "%s" "username:password" | base64)
# Basic dXNlcm5hbWU6cGFzc3dvcmQ=