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API Authentication (JWT)

API Authentication (JWT)

Continuing our journey, we're diving into API Authentication, specifically using JSON Web Tokens (JWTs). JWTs are a powerful tool for securing API endpoints and ensuring authorized access.

What is JWT (JSON Web Token)?

JWT, short for JSON Web Token, is an open standard that defines a compact and self-contained way to securely transmit information between parties as a JSON object.

JWT Structure

Internal Structure of JWT

JWT consists of three parts, separated by dots (.).
1. Header (encoded as Base64)
2. Payload (encoded as Base64)
3. Signature (created by signing the header and payload with a secret or public/private key pair)

JWT Header

The JWT Header contains information about the token, including its type (JWT) and the hashing algorithm used to create the signature.

JWT Payload

The JWT Payload contains the claims, which are statements about the token's subject. Claims can include user ID, roles, expiration time, and any other relevant information.

JWT Signature

The JWT Signature is generated by signing the header and payload with a secret or public/private key pair. It ensures that the token has not been tampered with.

JWT Verification

To verify a JWT, the recipient must have access to the same secret or public key used to sign the token. They validate the signature and check if the token has expired.

Why Should I Use JWTs?

JWTs offer several advantages:
Compact and Secure
Stateless
Self-contained
Cross-origin resource sharing (CORS) friendly'

JWT Use Cases

  • User authentication
  • Authorization and access control
  • Data exchange between microservices
  • Single sign-on (SSO)
  • API rate limiting

JWT Best Practices

  • Use a strong and secret algorithm for signing JWTs.
  • Set an appropriate expiration time for tokens.
  • Store the secret securely.
  • Invalidate tokens when necessary (e.g., password reset).
  • Use HTTPS for token transmission.

JWT Implementation in Node.js

const jwt = require("jsonwebtoken");

const token = jwt.sign({ userId: 123 }, "mySecret", { expiresIn: '1h' });

JWT Libraries for Node.js

  • jsonwebtoken
  • passport-jwt
  • express-jwt

JWT and Authentication

JWTs are commonly used in authentication mechanisms. When a user logs in, the server generates a JWT and sends it to the client. The client stores the JWT securely and includes it in subsequent requests to access protected resources.

JWT and Authorization

JWTs can also be used for authorization. The payload of the JWT can include information about the user's roles and permissions. When a user makes a request, the server can verify the JWT and grant access based on the user's permissions.

Next Up: API Rate Limiting

API Rate Limiting is a crucial topic in API design. In the next session, we'll explore techniques to control the number of requests an API can handle and prevent abuse. Follow us to learn more!