Useless Authorization Server

Overview

This is an implementation of authorization server just for education purposes only. This implementation is not proper for commercial use because the following reasons and unwritten ones.

• PKCE (RFC 7636), a must security feature, is not supported.
• Other flows than the authorization code flow are not supported.
• Confidential clients are not supported. Note that this implies that this implementation does not have any code related to client authentication.
• The 'redirect_uri' request parameter must always be given although RFC 6749 allows omission of the parameter in some cases.
• RFC 6749 allows redirect URIs to include a query part, but this implementation fails to build a proper value for the Location header in the case.
• It is not checked whether the same request parameters are not given although RFC 6749 requires that "Request and response parameters MUST NOT be included more than once."
• This implementation does not strictly follow the requirement in RFC 6749: "Parameters sent without a value MUST be treated as if they were omitted from the request."
• The authorization endpoint does not use 302 Found in error cases even after the redirect URI it should use has been determined.
• The value of the state request parameter is not checked although RFC 6749 requires that characters of state be in the range of %x20-7E.
• The token endpoint requires client_id as a mandatory parameter because it knows that all clients are 'public'.
• The token endpoint requires redirect_uri as a mandatory parameter because (1) it knows that the authorization endpoint always requires redirect_uri and (2) it does not support other flows than the authorization code flow.
• No mechanism to clean up expired authorization codes and access tokens periodically.
• Entropy of authorization codes and access tokens is too low.
• The feature of sinatra's session is used without any security consideration.
• No protection for CSRF.
• The following are hard-coded: One client application, one end-user account, access token duration.

Set up

$ gem install sinatra webrick
$ git clone https://github.com/authlete/useless-oauth-server
$ cd useless-oauth-server

Run

$ ruby server.rb

Test

Authorization Request and Response

Input the following URL to your web browser's address bar.

http://localhost:4567/authorization?response_type=code&client_id=1&redirect_uri=http://example.com/&scope=read+write

An authorization page will be displayed. Input john and john to the Login ID field and the Password field. Then, press the "Approve" button.

The top page of example.com will be displayed. Copy the value of the code parameter of the URL which is in the address bar of the web browser. The value is the issued authorization code.

Token Request and Response

Type the following commands.

$ CODE={The-Issued-Authorization-Code}
$ curl http://localhost:4567/token \
  -d grant_type=authorization_code \
  -d code=$CODE \
  -d client_id=1 \
  -d redirect_uri=http://example.com/

A successful response will look like the following.

{
  "access_token":"mvL_sRy3",
  "token_type":"Bearer",
  "expires_in":86400,
  "scope":"read write"
}