Web Authentication: Cookies vs. Tokens

In this article, you will get to learn how to Choose Between Cookies and Tokens in Web Authentication.

In today's digital landscape, ensuring the stability and security of the authentication mechanism is crucial for all applications. However, with numerous authentication methods available, choosing the right approach can be challenging. In this article, we will explore two popular authentication methods: token-based authentication and cookie-based authentication. By discussing their features, advantages, and disadvantages, and comparing their capabilities, you will gain valuable insights to determine the best approach for your project.

As the number of cybersecurity threats continues to rise, it is essential to implement a robust authentication mechanism. Authentication is the process of verifying the identity of users accessing an application or system. A reliable authentication method guarantees secure access, protects user data, and prevents unauthorized access.

Web Authentication: Cookies vs. Tokens

Here we have the difference between Cookies-Based Authentication vs Token-Based Authentication

Factors	Cookie-Based Authentication	Token-Based Authentication
Implementation Complexity	Simple	More complex
Storage Location	Browser	Client-side (usually browser storage or local storage)
Server Dependency	Requires server-side session management	Stateless - server only needs to validate tokens
Scalability	Can be challenging to scale with large user sessions	More scalable due to stateless nature
Security	Vulnerable to cross-site scripting (XSS) attacks	Vulnerable to XSS attacks if token is improperly handled
Revocation of Tokens	Not possible until token expiration	Can revoke tokens by maintaining a blacklist or using token expiration strategies
Compatibility with APIs	Not suitable for APIs	Suitable for APIs and can be used by various clients (e.g., mobile apps)
Data Storage	Can store additional user data in server-side sessions	Can include user data in the token itself (JWT claims)
Ease of Implementation	Browser handles cookie management	Requires manual token handling and inclusion in request headers
Granularity of Control	Limited control over individual requests	Fine-grained control over access by validating tokens

Now, let's have the detailed information on Web Authentication: Cookies vs Tokens

1. Cookie-Based Authentication

In cookie-based authentication, a unique identifier, known as a cookie, is created on the server-side and sent to the user's browser. This article delves into the workings of cookie-based authentication, highlighting its key components and discussing its features, advantages, and limitations. By understanding the inner workings of this authentication method, developers can make informed decisions about its implementation.

To understand better, we have divided the Cookie-Based Authentication Process into 5 parts:

STEP 1. User login

When a user logs into a web application using their credentials, the server validates the provided information and creates a session in the database. This session represents the authenticated user.

STEP 2. After the user submits their credentials, the server validates them to ensure their authenticity.

STEP 3. Cookies Generation

Upon successful authentication, the server responds to the user's browser by including a cookie in the Set-Cookie header. The cookie contains a unique identifier (cookie-value) and may include additional details such as an expiry date, domain, and path.

Example Set-Cookie Header:
 HTTP/2.0 200 OK 
 Content-Type: text/html 
 Set-Cookie: <cookie-name>=<cookie-value> 
 Set-Cookie: <cookie-name>=<cookie-value>; Expires=<date> 
 Set-Cookie: <cookie-name>=<cookie-value>; Max-Age=<number> 
 Set-Cookie: <cookie-name>=<cookie-value>; Domain=<domain> 
 Set-Cookie: <cookie-name>=<cookie-value>; Path=<path> 
 Set-Cookie: <cookie-name>=<cookie-value>; 
 Secure Set-Cookie: <cookie-name>=<cookie-value>; HttpOnly

4. Cookies Storage and Server Validation The user's browser stores the received cookie and automatically includes it with subsequent requests made to the server. The cookie acts as a unique identifier for the user.

When the server receives a request from the user's browser, it retrieves the associated cookie and compares the session ID stored within the cookie against the session in the database. This verification process ensures that the request is coming from an authenticated user.

5. Logout and Cookie Expiration

Upon user logout, the server removes the corresponding session from the database, effectively terminating the user's authenticated state. Additionally, the browser removes the cookie from its storage, ensuring its expiration.

Pros of Cookie-Based Authentication:

• Automated Process: Developers do not need to explicitly handle cookie inclusion in requests as the browser automatically manages this process.

• Simplified Implementation: Leveraging the browser's built-in cookie handling reduces the complexity of authentication implementation.

• Single-Origin Enforcement: Cookies by default only work on a single domain, which enhances security by enforcing single-origin behavior.

• Additional Data Storage: Cookies can be used to store additional data attached to the user session, such as personalization and access control information.

Cons of Cookie-Based Authentication:

• Potential Security Vulnerabilities: Cookie-based authentication is vulnerable to cross-site scripting (XSS) and cross-site request forgery (CSRF) attacks, which can be mitigated through additional security measures.

• Limited Control over Requests: Cookies are sent with every request, even if authentication is not required, resulting in unnecessary overhead.

• Single-Domain Limitation: Cookies are restricted to a single domain unless explicitly configured, which may pose challenges when integrating frontend and backend from different domains or subdomains.

• Unsuitability for APIs: Cookies are not suitable for APIs intended for non-browser clients like mobile apps, as managing cookies in such scenarios can be complex compared to token-based authentication.

• Scalability Concerns: Storing sessions in a database for each user can lead to scalability issues as the number of users grows, necessitating additional measures such as using in-memory databases like Redis.

• Overhead in Aggregated and Scaled Scenarios: While cookies can store additional data, such as user claims, the increased size of tokens may impact network utilization, particularly in scenarios with numerous aggregated and scaled requests.

2. Token-Based Authentication

Token-based authentication emerged as an alternative to address the limitations of cookie-based authentication. Unlike cookies, this approach requires manual implementation, and tokens are stored on the client side.

When a user logs in to a web application, the server verifies their credentials and generates an encrypted token. This token is then sent back to the browser, where it is stored and can be included in the authorization header of subsequent requests.

However, the implementation of token-based authentication is more intricate than the simplified flow described above. For example, OpenID Connect introduces multiple authentication flows to cater to different use cases.

To gain a better understanding of how tokens work, let's break down the process into four parts and use JWT (JSON Web Token), the most widely used token standard, as an example.

STEP 1. User login to the application using credentials.

STEP 2. The server verifies the credentials, generates a token, signs it with a secret key, and sends it back to the browser. Encryption measures like SSL should be used to secure the communication channel.

On the server side, libraries like jsonwebtoken can be used to generate these tokens.

// Install
npm install jsonwebtoken// Usage
var jwt = require('jsonwebtoken');
var token = jwt.sign(
              { data: user}, 
              privateKey, 
              { algorithm: 'RS256'},
              exp: Math.floor(Date.now() / 1000) + (60 * 60),            );

A token generated from jsonwebtoken library would look like below:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

The generated token consists of three parts: header, payload, and signature (header.payload.signature), separated by periods. Tools like jwt.io can be used to parse and examine the token information.

STEP 3. The token is stored in browser storage, and JavaScript is used to add it to subsequent requests.

The browser can store the token in Local Storage, Session Storage, or Cookie Storage. It is then added to the authorization header of relevant requests, using JavaScript, for server-side request validation. The token can be included in the header as follows:

Authorization: Bearer <token>

The jsonwebtoken library also provides a jwt.decode() function to decode the token and access the payload data within the application.

STEP 4. When the user logs out, the token needs to be manually deleted from storage. Upon user logout, the token stored in the storage must be cleared manually, rendering it inaccessible for further requests.

Pros of Token-Based Authentication:

1. Stateless mechanism: Token-based authentication is stateless, meaning it does not require the server to store any user information. This simplifies the architecture and allows for more scalable solutions compared to cookie-based authentication.

2. Scalability: Since the server does not need to maintain user sessions or store session data, token-based authentication enables better scalability. This is particularly beneficial for applications with a large user base or high traffic volume.

3. Enhanced security: Tokens provide a higher level of security compared to cookies. They can mitigate certain vulnerabilities associated with cookies, such as cross-site scripting (XSS) attacks, by minimizing the exposure of sensitive information.

4. Granular control: Tokens offer the flexibility to include additional information (claims) within the token payload, allowing for fine-grained control over user access and authorization. This can be useful for implementing role-based access control (RBAC) or other authorization mechanisms.

Cons of Token-Based Authentication:

1. Vulnerability to XSS attacks: While tokens aim to address security issues related to cookies, they are not completely immune to attacks. If an application allows external JavaScript code to be embedded, tokens stored in the browser can be susceptible to cross-site scripting (XSS) attacks.

2. Token exposure: Since tokens are stateless and stored on the client side, if a token is exposed to an unauthorized party, there is no way to invalidate or revoke it until its expiration time. It is crucial to minimize the token's lifespan and adopt proper token management practices to mitigate this risk.

3. Complexity of implementation: Token-based authentication requires manual implementation, which can be more complex compared to the automated process of cookie-based authentication. Developers need to handle token generation, validation, and storage, as well as ensure the secure transmission of tokens.

4. Increased payload size: Tokens can be larger in size compared to cookies, especially when they include additional claims or information. This can impact network utilization, particularly in scenarios where tokens need to be sent with each request, potentially increasing bandwidth usage.

Conclusion

Token-based and cookie-based approaches are two of the most commonly used authentication mechanisms for web applications. In this article, we explored the inner workings of both methods, their features, advantages, and disadvantages.

It is important to note that neither of these methods is flawless and they come with their own set of drawbacks. However, instead of searching for a perfect solution, it is recommended to select an authentication method based on your specific project requirements.

By carefully considering factors such as scalability, security needs, compatibility with different client types (e.g., browsers, mobile apps), and the level of control you require over user sessions, you can make an informed decision regarding the authentication approach that best suits your project.