Last updated on Jul 7, 2024

What are the best practices for authentication and authorization in Flask Web Applications?

Flask is a popular and lightweight Python web framework that allows you to create web applications with minimal code and configuration. However, building secure and robust web applications also requires implementing authentication and authorization mechanisms that protect your users' data and access rights. In this article, you will learn what are the best practices for authentication and authorization in Flask web applications, and how to use some of the most common tools and libraries for this purpose.

1 What is authentication and authorization?

Authentication is the process of verifying the identity of a user who wants to access your web application. Authorization is the process of granting or denying access to specific resources or actions based on the user's role, permissions, or other criteria. For example, you may want to allow only registered users to log in to your web application, and only admins to edit or delete posts.

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Denys Dobrelya

AI Security and MultiCloud Expert: AWS, Google, Oracle
In my sample Flask apps, I always try to explain the difference between authentication and authorization, which boils down to this: 1. Authentication asks: Who are you? 2. Authorization asks: What can you do? Think of it like entering a building with high security. _Authentication_ is like showing your ID at the entrance. It verifies your identity and confirms you're allowed to be there. _Authorization_ is like getting a specific keycard after being identified. This keycard determines which areas you can access (e.g., elevators, offices) within the building.
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Pradeep kumar Saraswathi

User Interface Architect | Leader in Building Digital platforms | CMS & DXP | Web & AI
Authentication and Authorization are two fundamental concepts in web application security, often abbreviated as AuthN and AuthZ respectively. Authentication : When a user logs into a web application with their username and password, the system checks these credentials against a stored record to verify their identity. Authorization: After a user logs in, the system checks their role to decide if they have the right to edit or delete posts (authorization). An admin might have full access, while a regular user can only view posts.
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2 How to implement authentication in Flask?

One of the easiest ways to implement authentication in Flask is to use Flask-Login, an extension that provides user session management and login functionality. Flask-Login works with any user model that has an id attribute and implements four methods: is_authenticated, is_active, is_anonymous, and get_id. You can use Flask-Login to create a login form, a logout route, a login_required decorator, and a current_user variable that stores the logged-in user's information.

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Pradeep kumar Saraswathi

User Interface Architect | Leader in Building Digital platforms | CMS & DXP | Web & AI
Flask-Login is a useful extension for managing user sessions in Flask applications. It handles common tasks like logging in, logging out, and remembering users' sessions. First, install Flask-Login. Set up a user model and initialize Flask-Login. Create registration and login forms. Define routes for registration, login, and logout. Ensure the database is created, and run the application. This setup manages user sessions, registration, and login securely, using Flask-Login and best practices for password handling.
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3 How to implement authorization in Flask?

One of the simplest ways to implement authorization in Flask is to use Flask-Principal, an extension that provides identity and permission management. Flask-Principal uses the concepts of identity, role, and permission to define who can do what in your web application. You can use Flask-Principal to create roles, assign permissions, and check permissions using decorators or signals. For example, you can use the RoleNeed and Permission classes to create a admin permission that requires the user to have the admin role.

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Pradeep kumar Saraswathi

User Interface Architect | Leader in Building Digital platforms | CMS & DXP | Web & AI
Implementing authorization in Flask using Flask-Principal involves several steps. first install the Flask-Principal package. Then, set up your Flask application and initialize Flask-Principal. Define roles and permissions specifying the roles required to access each route.
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4 How to use passwords and tokens in Flask?

Passwords and tokens are two common ways to authenticate users and secure your web application. Passwords are strings that users enter to prove their identity, while tokens are strings that are generated by the server and sent to the user as a response to a successful authentication. You can use passwords and tokens in Flask by using Flask-Bcrypt and Flask-JWT-Extended, two extensions that provide hashing and tokenization functionality. Flask-Bcrypt allows you to hash and verify passwords using the bcrypt algorithm, which is a secure and slow hashing method that prevents brute-force attacks. Flask-JWT-Extended allows you to create and decode JSON Web Tokens (JWTs), which are encrypted and signed tokens that contain user data and expiration time.

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Pradeep kumar Saraswathi

User Interface Architect | Leader in Building Digital platforms | CMS & DXP | Web & AI
Flask-JWT-Extended is used mostly for token generation and management. Flask-JWT-Extended enables the creation and management of JSON Web Tokens (JWTs) for secure user authentication. After setting up the extension, hash passwords before storing them and generate JWTs upon successful login. Secure routes by requiring JWTs for access, ensuring that only authenticated users can reach protected endpoints.
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5 How to use OAuth and OpenID in Flask?

OAuth and OpenID are two protocols that allow users to authenticate and authorize using third-party services, such as Google, Facebook, or Twitter. OAuth allows users to grant access to their data or resources on one service to another service, without sharing their credentials. OpenID allows users to log in to one service using their identity on another service, without creating a new account. You can use OAuth and OpenID in Flask by using Flask-OAuthlib and Flask-OpenID, two extensions that provide integration with these protocols. Flask-OAuthlib allows you to create OAuth clients and servers, and handle requests and responses. Flask-OpenID allows you to create OpenID consumers and providers, and validate identities and attributes.

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6 How to test and debug authentication and authorization in Flask?

Testing and debugging authentication and authorization in Flask is essential for the security and functionality of your web application. To do so, you can use various tools and techniques such as Flask-Testing and unittest to create unit tests and integration tests, with coverage and report options. Additionally, you can use Flask-DebugToolbar and Flask-Shell-Plus to inspect and interact with variables, requests, responses, sessions, cookies, and database. Moreover, Flask-Talisman and Flask-WTF can be used to enforce HTTPS and CSRF protection to prevent common web attacks. You should also use logging and error handling to record exceptions, errors, and warnings that occur in your web application, displaying them in an accessible way.

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7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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What are the best practices for authentication and authorization in Flask Web Applications?

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1 What is authentication and authorization?

2 How to implement authentication in Flask?

3 How to implement authorization in Flask?

4 How to use passwords and tokens in Flask?

5 How to use OAuth and OpenID in Flask?

6 How to test and debug authentication and authorization in Flask?

7 Here’s what else to consider

Web Applications

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What are the best practices for authentication and authorization in Flask Web Applications?

1

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3

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5

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7

1 What is authentication and authorization?

2 How to implement authentication in Flask?

3 How to implement authorization in Flask?

4 How to use passwords and tokens in Flask?

5 How to use OAuth and OpenID in Flask?

6 How to test and debug authentication and authorization in Flask?

7 Here’s what else to consider

Web Applications

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