How can JWT be used?
JWT stands for JSON web token. It is a compact, URL-safe means of representing claims to be transferred between two parties. The claims in a JWT are typically used to provide authentication and information about an authenticated user.
Now let’s talk in simple English. Think of a JWT like a digital passport. It contains information about you, like your name and maybe some permissions. It’s used when you want to access certain online services or resources, like logging into a website or using an app.
When you log in, you get this passport (JWT). Then, whenever you want to do something that requires you to prove who you are, you show this passport. The website or app can quickly check it to see if it’s valid and if you’re allowed to do what you’re asking. This is the main concept of JWT. I hope you’ve understood, what JWT is and why it is used.
JWTs consist of three parts separated by dots: a header, a payload, and a signature. The header typically consists of metadata about the token such as the type of token and the signing algorithm used. The payload contains the claims, which are statements about the user and any additional data. The signature is used to verify that the message wasn’t changed along the way, and it can also ensure that the sender of the JWT is who it says it is and to ensure that the message wasn’t tampered with.
Now let’s get familiar with three common uses of JWT
1. Authentication
JWTs can be used to securely authenticate users. After a user logs in, a JWT containing user information (such as username or user ID) can be generated on the server and sent to the client. The client then includes this JWT in subsequent requests to authenticate itself to the server.
Example: A user logs in to a web application using their username and password. Upon successful authentication, the server generates a JWT containing the user’s ID and possibly other information such as their role. This JWT is then sent to the client, which includes it in the HTTP headers of subsequent requests to access protected resources.
2. Authorization
JWTs can also be used to control access to resources by including authorization information in the token. This allows servers to determine whether a client has the necessary permissions to access a particular resource without having to look up the user’s information in a database.
Example: A web application has different levels of access for users, such as regular users and administrators. After a user logs in, the server generates a JWT containing the user’s role (e.g., “user” or “admin”). When the user tries to access a protected resource, the server checks the JWT to determine whether the user has the necessary permissions.
3. Information exchange
JWTs can be used to securely exchange information between parties. Because JWTs are digitally signed, the receiving party can verify that the information contained in the token has not been tampered with.
Example: In a microservices architecture, different services need to communicate with each other. Instead of passing sensitive information (such as user credentials) between services, JWTs can be used to securely exchange information. For example, when a user logs in to the authentication service, it can generate a JWT containing the user’s ID and send it to other services. These services can then use the JWT to authenticate the user and access their information.
Conclusion
Overall, JWTs are versatile and can be used in various scenarios where secure authentication, authorization, and information exchange are required.
