Aug 11

Implementing JWT Authentication in Spring Boot with MongoDB

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JSON Web Token (JWT) is an open standard for securely transmitting information as a JSON object. It's digitally signed using HMAC or RSA/ECDSA, ensuring the data's integrity and authenticity.

📌 Why JWT?

  • Authorization: Post-login, JWTs allow users to access permitted routes, services, and resources without re-authenticating.
  • Information Exchange: Securely transmit information, ensuring the sender's identity and data integrity.

🔍 JWT Structure:

1. Header: Specifies the token type and signing algorithm.
{ "alg": "HS256", "typ": "JWT" }

2. Payload: Contains claims (user data and metadata).
{ "sub": "1234567890", "name": "John Doe", "admin": true }

3. Signature: Verifies the token's integrity.
HMACSHA256(base64UrlEncode(header) + "." + base64UrlEncode(payload), secret)

🔄 How JWT Works in Spring Boot:

1. User Authentication: User logs in, and the server issues a JWT.

2. Token Usage: For subsequent requests, the client sends the JWT in the Authorization header.

Authorization: Bearer <token>

3. Server Validation: The server verifies the token's signature and grants access to protected resources if valid.

Avoid storing sensitive data in JWT payloads and ensure tokens are short-lived to enhance security.

The benefits of using JWT:

  • Statelessness: No need to store session data on the server.
  • Scalability: Ideal for distributed systems.
  • Security: Tokens can be signed and encrypted.

High-Level Process

  • User Registration: Users can register by providing their credentials (username and password). In our application, the password is securely hashed using bcrypt before being stored in MongoDB.

  • User Login: During login, the user submits their credentials. The server verifies these credentials against the data stored in MongoDB. If authentication is successful, the server generates a JWT and sends it back to the client.

  • Token Storage: The generated JWT is sent to the client, typically stored in local storage or cookies. This token will be used for future requests to secure endpoints.

  • Protected Routes: For subsequent requests to protected routes, the client includes the JWT in the authorization header. The server extracts the token, verifies its validity, and grants access to the requested resources if the token is valid.

Download Code: You can download the complete code example which I have explained in above video from below.
You can also check Java Spring Boot Interview Playbook here: Link
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