How do you use HTTP cookies, sessions, and tokens for web authentication and authorization?

1 HTTP cookies

HTTP cookies are small pieces of data that are sent by the server to the client, and stored by the browser. They can be used to store user preferences, track user behavior, or maintain user sessions. For authentication and authorization, cookies can store a unique identifier that links the user to a server-side record of their credentials and roles. The browser sends the cookie back to the server with every request, so the server can verify the user's identity and permissions. However, cookies have some drawbacks, such as being vulnerable to theft, forgery, or cross-site scripting attacks, and being limited by size and number.

2 HTTP sessions

HTTP sessions are a way of maintaining stateful communication between the client and the server, despite HTTP being a stateless protocol. Sessions use cookies or other methods to store a session ID on the client side, and associate it with a server-side data structure that contains the user's information and state. Sessions can store more data than cookies, and can be more secure if the session ID is encrypted or regenerated frequently. However, sessions also have some challenges, such as requiring server-side memory or storage, being difficult to scale across multiple servers, or being affected by network failures or timeouts.

3 HTTP tokens

HTTP tokens are another way of implementing stateless authentication and authorization, without relying on cookies or sessions. Tokens are self-contained pieces of data that encode the user's identity, permissions, and other claims, and are signed by the server using a secret key or a public-private key pair. Tokens are sent by the server to the client, and stored by the browser in local storage or memory. The client sends the token back to the server with every request, and the server validates the token's signature and payload. Tokens can be more flexible, portable, and scalable than cookies or sessions, and can support cross-domain and cross-origin requests. However, tokens also have some limitations, such as being harder to revoke, being susceptible to replay attacks, or being dependent on cryptographic algorithms and keys.

4 Cookie-based vs token-based authentication

Cookie-based and token-based authentication are two common approaches to implement web authentication and authorization, and each one has its own pros and cons. Cookie-based authentication relies on the server to manage the user's session and state, and uses cookies to store and transmit the session ID. Token-based authentication relies on the client to store and transmit the user's information and claims, and uses tokens to encode and sign them. Cookie-based authentication can be simpler to implement, more compatible with browsers, and easier to revoke. Token-based authentication can be more efficient, secure, and flexible, and support more scenarios and platforms.

5 How to choose the best method

When deciding which method is the best for web authentication and authorization, there is no definite answer as it depends on various factors such as the type, size, and complexity of the web application, the security and performance requirements, user experience and expectations, and available technologies and standards. Generally speaking, cookies should be used if stateful communication between the client and server is needed or if existing browser features and frameworks that support cookies are to be leveraged. Tokens should be used if stateless communication between the client and server is necessary or if cross-domain and cross-origin requests need to be enabled. A combination of cookies and tokens can be used to achieve a balance between statefulness and statelessness or to enhance the security and functionality of your web application.