🎗️ JWT

• JSON Web Token (JWT) authentication is a method of securely authenticating users and allowing them to access protected resources on a website or application.
• It's a popular and widely used method of web authentication as it allows for easy and secure user authentication without the need for the server to maintain a session state.
• In this process, the server generates a signed JWT and sends it to the client. The client then includes this token in subsequent requests to the server to authenticate themselves. The JWT is usually stored in the browser's localStorage and sent as part of the request's headers.
• The JWT is usually stored in the browser's localStorage and sent as part of the request's headers.
• To authenticate a client using JWT, the server first generates a signed JWT and sends it to the client. The client then includes the JWT in the header (usually the authorization header) of subsequent requests to the server. The server then decodes the JWT and verifies the signature to ensure that a trusted party sent it. If the signature is valid, the server can then use the information contained in the JWT to authenticate the client and authorize their access to specific resources.

Components of JWT

• The header: consists of two parts—the token type, which is JWT, and a signing algorithm, such as HMAC-SHA256 or RSA
• The payload: contains the claims—in other words, the statements about an entity (typically, the user) and additional data
• The signature: used to verify the JWT's integrity

Pros and Cons of JWT

Advantages of Using JWT

1. JWT authentication is stateless: A JWT contains all the information regarding the user's identity and authentication, including the claims. This can be more efficient than storing session information on the server as it reduces the amount of data that needs to be stored and retrieved for each request.

2. Create anywhere: Another advantage of JWT authentication is that the token can be generated from anywhere, including external services or third-party applications. This allows for flexibility in terms of where and how the token is generated, which can be useful in a microservices architecture where different services may need to authenticate users.

3. Fine-grained access control: JWT can contain information about the user's role and permissions in the form of claims. This gives the application developers a lot of control over what actions a user is allowed to take.

disadvantages of using JWT authentication:

1. Hard to invalidate: Invalidating JWTs is only possible if you maintain a list on a shared database, which introduces additional overhead. The database is necessary because if you need to revoke a token or if a user's permissions change, the server won't otherwise be able to determine the status of the token and might give access when it shouldn't. If the JWTs you're using are long-lived—in other words, they have a very long (or no) expiration time specified—it becomes even more important that they're stored in an accessible database.
2. Size and security concerns: JWTs can sometimes contain unnecessary information that might be useless for the application and, at the same time, make the token larger and more cumbersome to work with. If the JWT is unencrypted, it can also end up revealing too much about the user.