authl 0.0.2

Genericized multi-protocol authentication wrapper

Authl

A library for managing federated identity

Current state

Currently supported:

• Directly authenticating against email
• Federated authentication against IndieLogin
• Test/loopback authentication

Design goals

High-level goal: Make it easy to provide federated identity to Python 3-based web apps (with a particular focus on Publ)

This library should enable the following:

• Given a URL, determine whether an identity can be established against that URL
• Provide multiple identity backends for different URL schemata, including but not limited to:
  • OpenID 1.x
  • IndieAuth
  • Email
  • Various OAuth providers (twitter, facebook, etc.)
  • Mastodon
  • Local username/password
• Each backend should be optional and configurable
• Provide default (optional) Flask endpoints for the various endpoints (URL validation, success callbacks, etc.)

Roadmap

Rough expected order of implementation:

1. Email magic links (which provides access for basically everyone) DONE
2. IndieAuth (possibly using IndieLogin.com for the hard parts) DONE
3. OpenID 1.x (which provides access for Dreamwidth, Wordpress, Launchpad, and countless other site users)
4. Everything else

Rationale

Identity is hard, and there are so many competing standards which try to be the be-all end-all Single Solution. Many of them are motivated by their own politics; OAuth wants lock-in to silos, IndieAuth wants every user to self-host their own identity fully and not support silos at all, etc., and users just want to be able to log in with the social media they're already using (siloed or not).

Any solution which requires all users to have a certain minimum level of technical ability is not a workable solution.

All of these solutions are prone to the so-called "NASCAR problem" where every supported login provider needs its own UI. But being able to experiment with a more unified UX might help to fix some of that.

Usage

This is just in its early experimental phase and the API is subject to change. However, if you would like to use it anyway, see test.py in the project source, which provides a minimal Flask app that does nothing but ask for an identity to log in as, and validates that identity.

The basic flow is as follows:

1. Create an Authl object with your configured handlers

   At present, the only useful handlers are email_addr and indieauth.

2. Make endpoints for initiation and progress callbacks

   The initiation callback receives an identity string (email address/URL/etc.) from the user, queries Authl for the handler and its ID, and builds a callback URL for that handler to use. Typically you'll have a single callback endpoint that includes the handler's ID as part of the URL scheme.

   The callback endpoint needs to be able to receive a GET or POST request and use that to validate the returned data from the authorization handler.

   Your callback endpoint (and generated URL thereof) should also include whatever intended forwarding destination.

3. Handle the authl.disposition object types accordingly

   A disposition is what should be done with the agent that initiated the endpoint call. Currently there are the following:

   • Redirect: return an HTTP redirection to forward it along to another URL
   • Notify: return a notification to the user that they must take another action (e.g. checking their email)
   • Verified: indicates that the user has been verified; set a session cookie (or whatever) and forward them along to their intended destination
   • Error: An error occurred; return it to the user as appropriate

Flask usage

To make life easier with Flask, Authl provides an authl.setup_flask convenience function. You can use it from a Flask app with something like the below:

import uuid
import logging

import flask
import authl

logging.basicConfig(level=logging.INFO)
LOGGER = logging.getLogger(__name__)

# Create a Flask application and give it a randomly-generated signing key
app = flask.Flask('authl-test')
app.secret_key = str(uuid.uuid4())

# Configure the default Flask endpoints
authl.setup_flask(
    app,
    {
        'SMTP_HOST': 'localhost',
        'SMTP_PORT': 25,
        'EMAIL_FROM': '[e-mail]',
        'EMAIL_SUBJECT': 'Login attempt for Authl test',
        'INDIELOGIN_CLIENT_ID': 'http://localhost',
    },
)

# Here's a simple page handler which just shows a login link if you're logged out
# and vice versa
@app.route('/')
@app.route('/some-page')
def index():
    if 'me' in flask.session:
        return 'Hello {me}. Want to <a href="{logout}">log out</a>?'.format(
            me=flask.session['me'],
            logout=flask.url_for('logout', redir=flask.request.path[1:])
        )

    return 'You are not logged in. Want to <a href="{login}">log in</a>?'.format(
        login=flask.url_for('login', redir=flask.request.path[1:]))

# And here's a means of logging out
@app.route('/logout/')
@app.route('/logout/<path:redir>')
def logout(redir=''):
    flask.session.clear()
    return flask.redirect('/' + redir)

This will configure the Flask app to allow IndieLogin and email-based authentication (using the server's local sendmail), and use the default login endpoint of /login/. The index() endpoint handler always redirects logins and logouts back to the same page when you log in or log out (the [1:] is to trim off the initial / from the path). The logout handler simply clears the session and redirects back to the redirection path.

The above configuration uses Flask's default session lifetime of one month (this can be configured by setting app.permanent_session_lifetime to a timedelta object, e.g. app.permanent_session_lifetime = datetime.timedelta(hours=20)). Sessions will also implicitly expire whenever the application server is restarted, as app.secret_key is generated randomly at every startup.