Unlocking the Power of JWT Authentication: A Step-by-Step Guide

Bearing Authentication: The Key to Secure APIs

Bearer authentication, also known as token authentication, is an HTTP authentication scheme that employs secret strings or security tokens, known as Bearer tokens. These tokens are cryptographically generated strings, typically produced by the server upon a login request from the client. When accessing resources that require authentication, the client must send this token in the Authorization header.

The Importance of Bearer Tokens

So, why do we need to use Bearer in front of the token? The answer lies in the Authorization: pattern introduced by the W3C in HTTP 1.0. This pattern allows for multiple methods of authorization, making it essential to distinguish between them. By using Bearer, we ensure interoperability and adherence to W3C norms.

Exporting to REST Endpoints

To create a REST API-based Express.js server, we need to export the right functions from our dec-enc.js file. We’ll add export statements and modify the code to work with the REST endpoint. Our goal is to convert the claims, key, and header into parameters of the encode function.

export function generateJwt(claims, key, header) {
  // implementation
}

export function verifyJwt(token, key) {
  // implementation
}

export function validateJwt(token) {
  // implementation
}

Creating the REST API Endpoint

Let’s create a basic Express.js server, app.js, and define the routes for our API calls. We’ll use the express.json() middleware to parse incoming requests with JSON payloads. Our API routes will include endpoints for signing in, getting an existing token, signing out, and utilizing Bearer authentication headers.

const express = require('express');
const app = express();
app.use(express.json());

app.post('/signin', (req, res) => {
  // implementation
});

app.get('/token', (req, res) => {
  // implementation
});

app.post('/signout', (req, res) => {
  // implementation
});

app.use((req, res, next) => {
  const token = req.header('Authorization').replace('Bearer ', '');
  // implementation
});

Implementing the Routes

We’ll call the three methods with the right parameters from the user’s request object. The request object will contain information sent by the client browser or user to the server, and we’ll use the response object to send data back to the client.

app.post('/signin', (req, res) => {
  const claims = req.body.claims;
  const key = req.body.key;
  const header = req.body.header;
  const token = generateJwt(claims, key, header);
  res.json({ token });
});

app.get('/token', (req, res) => {
  const token = req.header('Authorization').replace('Bearer ', '');
  const isValid = validateJwt(token);
  if (isValid) {
    res.json({ token });
  } else {
    res.status(401).json({ error: 'Invalid token' });
  }
});

app.post('/signout', (req, res) => {
  const token = req.header('Authorization').replace('Bearer ', '');
  // implementation
  res.json({ message: 'Signed out successfully' });
});

Testing the API Endpoints

Each of the three functions returns a valid JavaScript object. We can send the response in JSON format using res.json() and passing the return value of the functions. To test our API endpoints, we can use a tool like Postman, which allows us to examine responses and verify the output.

• Create a new request in Postman and set the method to POST.
• Set the request URL to undefined/signin.
• In the request body, add the required parameters (e.g., claims, key, and header).
• Send the request and examine the response.