Flask-DigestAuth 0.5.0

Why HTTP Digest Authentication?

HTTP Digest Authentication has the advantage that it does not send thee actual password to the server, which greatly enhances the security. It uses the challenge-response authentication scheme. The client returns the response calculated from the challenge and the password, but not the original password.

Log in forms has the advantage of freedom, in the senses of both the visual design and the actual implementation. You may implement your own challenge-response log in form, but then you are reinventing the wheels. If a pretty log in form is not critical to your project, HTTP Digest Authentication should be a good choice.

Flask-DigestAuth works with Flask-Login. Log in protection can be separated with the authentication mechanism. You can create protected Flask modules without knowing the actual authentication mechanisms.

Simple Applications with Flask-DigestAuth Alone

In your my_app.py:

from flask import Flask, request, redirect
from flask_digest_auth import DigestAuth

app: flask = Flask(__name__)
... (Configure the Flask application) ...

auth: DigestAuth = DigestAuth()
auth.init_app(app)

@auth.register_get_password
def get_password_hash(username: str) -> t.Optional[str]:
    ... (Load the password hash) ...

@auth.register_get_user
def get_user(username: str) -> t.Optional[t.Any]:
    ... (Load the user) ...

@app.get("/admin")
@auth.login_required
def admin():
    return f"Hello, {g.user.username}!"

@app.post("/logout")
@auth.login_required
def logout():
    auth.logout()
    return redirect(request.form.get("next"))

Larger Applications with create_app() with Flask-DigestAuth Alone

In your my_app/__init__.py:

from flask import Flask
from flask_digest_auth import DigestAuth

auth: DigestAuth = DigestAuth()

def create_app(test_config = None) -> Flask:
    app: flask = Flask(__name__)
    ... (Configure the Flask application) ...

    auth.init_app(app)

    @auth.register_get_password
    def get_password_hash(username: str) -> t.Optional[str]:
        ... (Load the password hash) ...

    @auth.register_get_user
    def get_user(username: str) -> t.Optional[t.Any]:
        ... (Load the user) ...

    return app

In your my_app/views.py:

from my_app import auth
from flask import Flask, Blueprint, request, redirect

bp = Blueprint("admin", __name__, url_prefix="/admin")

@bp.get("/admin")
@auth.login_required
def admin():
    return f"Hello, {g.user.username}!"

@app.post("/logout")
@auth.login_required
def logout():
    auth.logout()
    return redirect(request.form.get("next"))

def init_app(app: Flask) -> None:
    app.register_blueprint(bp)

Simple Applications with Flask-Login Integration

In your my_app.py:

import flask_login
from flask import Flask, request, redirect
from flask_digest_auth import DigestAuth

app: flask = Flask(__name__)
... (Configure the Flask application) ...

login_manager: flask_login.LoginManager = flask_login.LoginManager()
login_manager.init_app(app)

@login_manager.user_loader
def load_user(user_id: str) -> t.Optional[User]:
    ... (Load the user with the username) ...

auth: DigestAuth = DigestAuth()
auth.init_app(app)

@auth.register_get_password
def get_password_hash(username: str) -> t.Optional[str]:
    ... (Load the password hash) ...

@app.get("/admin")
@flask_login.login_required
def admin():
    return f"Hello, {flask_login.current_user.get_id()}!"

@app.post("/logout")
@flask_login.login_required
def logout():
    auth.logout()
    # Do not call flask_login.logout_user()
    return redirect(request.form.get("next"))

Larger Applications with create_app() with Flask-Login Integration

In your my_app/__init__.py:

from flask import Flask
from flask_digest_auth import DigestAuth
from flask_login import LoginManager

auth: DigestAuth = DigestAuth()

def create_app(test_config = None) -> Flask:
    app: flask = Flask(__name__)
    ... (Configure the Flask application) ...

    login_manager: LoginManager = LoginManager()
    login_manager.init_app(app)

    @login_manager.user_loader
    def load_user(user_id: str) -> t.Optional[User]:
        ... (Load the user with the username) ...

    auth.init_app(app)

    @auth.register_get_password
    def get_password_hash(username: str) -> t.Optional[str]:
        ... (Load the password hash) ...

    return app

In your my_app/views.py:

import flask_login
from flask import Flask, Blueprint, request, redirect
from my_app import auth

bp = Blueprint("admin", __name__, url_prefix="/admin")

@bp.get("/admin")
@flask_login.login_required
def admin():
    return f"Hello, {flask_login.current_user.get_id()}!"

@app.post("/logout")
@flask_login.login_required
def logout():
    auth.logout()
    # Do not call flask_login.logout_user()
    return redirect(request.form.get("next"))

def init_app(app: Flask) -> None:
    app.register_blueprint(bp)

The views only depend on Flask-Login, but not the actual authentication mechanism. You can change the actual authentication mechanism without changing the views.

A unittest Test Case

from flask import Flask
from flask_digest_auth import Client
from flask_testing import TestCase
from my_app import create_app

class MyTestCase(TestCase):

    def create_app(self):
        app: Flask = create_app({
            "TESTING": True,
            "SECRET_KEY": token_urlsafe(32),
            "DIGEST_AUTH_REALM": "admin",
        })
        app.test_client_class = Client
        return app

    def test_admin(self):
        response = self.client.get("/admin")
        self.assertEqual(response.status_code, 401)
        response = self.client.get(
            "/admin", digest_auth=(USERNAME, PASSWORD))
        self.assertEqual(response.status_code, 200)

A pytest Test

import pytest
from flask import Flask
from flask_digest_auth import Client
from my_app import create_app

@pytest.fixture()
def app():
    app: Flask = create_app({
        "TESTING": True,
        "SECRET_KEY": token_urlsafe(32),
        "DIGEST_AUTH_REALM": "admin",
    })
    app.test_client_class = Client
    yield app

@pytest.fixture()
def client(app):
    return app.test_client()

def test_admin(app: Flask, client: Client):
    with app.app_context():
        response = client.get("/admin")
        assert response.status_code == 401
        response = client.get(
            "/admin", digest_auth=(USERNAME, PASSWORD))
        assert response.status_code == 200