Understanding OAuth and JWT in Backend Development

When building web applications for schools and universities, it’s really important to know about authentication and authorization. Two popular methods you might hear about are OAuth and JWT (JSON Web Tokens). Both of these are great for keeping web applications safe, but they do different things. Let’s look at how OAuth and JWT work and what makes them unique.

What is OAuth?

OAuth helps give limited access to user accounts over the internet. It lets other apps access some of your information without giving them your password. With OAuth, a user (that’s you!) can trust that the third-party apps are allowed to access certain things while keeping their login details safe.

How Does OAuth Work?

The OAuth process usually goes like this:

1. Authorization Request: You start by letting a third-party app access your information.
2. Authorization Grant: This shows how the app will get permission (there are different types of grants).
3. Access Token Request: The app then gets an access token based on your permission.
4. Access Protected Resource: Finally, the app uses that access token to get your data.

When Do People Use OAuth?

• Third-party Access: This is often used when apps want to get your personal info, like when a game wants to access your social media friends.
• Limited Sharing: It helps users share specific information, like pictures or files, without giving away their login info.

What is JWT?

JWT is a small, safe way of sharing information between two parties. It uses a compact structure that is easy to send online and can be trusted because it's signed digitally.

What Makes Up a JWT?

A JWT has three main parts:

• Header: This shows how the token is put together and what method was used to sign it.
• Payload: This part contains the actual information or claims about the user. It can have different types of claims.
• Signature: This part verifies that the token hasn't been changed. It combines the header, payload, secret key, and method used to sign it.

A JWT looks something like this:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

When Do People Use JWT?

• Authentication: JWT is great for securely sending user information that can be verified. It’s often used after you log in.
• Information Exchange: JWT can carry different bits of information back and forth between people who need it.

Key Differences Between OAuth and JWT

Even though OAuth and JWT are related, they have different main purposes:

1. Purpose:

   • OAuth: Focuses on giving limited access. It lets users let third-party apps use some of their information without sharing passwords.
   • JWT: Is a token type used for both checking who you are and sharing information. It doesn’t handle permissions by itself but is often used with APIs to check access.

2. How They Work:

   • OAuth: Works through a series of steps that involve the user, the app, and servers.
   • JWT: Simply carries user information as a token, so no extra steps are needed once you're logged in.

3. Where They Are Used:

   • OAuth: Commonly used where apps need to do things on your behalf, like accessing your documents in the cloud.
   • JWT: Good for managing sessions and sharing user information, especially in single-page applications (SPAs).

4. Token Management:

   • OAuth: Tokens can have different time limits. Sometimes you need to refresh them to keep access. This means you might get new tokens without having to log in again.
   • JWT: These tokens include their own expiration date. Once they are created, they don’t need ongoing checks unless they’re revoked.

5. Security:

   • OAuth: Checks tokens with the resource server, which means they can be revoked if needed.
   • JWT: The server can check if the token is valid on its own, but once issued, it can’t be easily revoked until it expires.

Security Tips

Both OAuth and JWT involve some security risks:

• OAuth:

  • Token Leakage: If someone gets hold of your access token, they could access your data without permission.
  • Grant Security: Each grant type has its own weaknesses, so developers must write secure code.

• JWT:

  • Token Lifetime: Setting an expiration date is important to reduce the chance of misuse.
  • Algorithm Choice: Using weak signing methods can make JWTs easier to hack.

Conclusion

In short, while OAuth and JWT can work well together to keep web applications safe, they do different jobs. OAuth focuses on granting permission, allowing apps to share user data without giving them passwords. Meanwhile, JWT is a flexible way of passing user information securely.

When building applications, knowing how these technologies differ will help developers choose the right approach. This ensures that users have a safe and easy experience when accessing their information. It's important for both teachers and students in web development classes to learn about OAuth and JWT, understand their strengths, and see how they can work together to create secure web applications.