Node (Express) API: Authorization

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By Andres Aguiar
Auth0

Sample Project

Download a sample project specific to this tutorial configured with your Auth0 API Keys.

System Requirements
  • express.js 4.4.0
  • express-jwt 5.1.0
  • express-jwt-authz 1.0.0
Show requirements

This tutorial shows you how to use the authorization features in the OAuth 2.0 framework to limit access to your or third-party applications. For more information, read the API authorization documentation.

Create a Resource Server (API)

In the APIs section of the Auth0 dashboard, click Create API. Provide a name and an identifier for your API. You will use the identifier as an audience later, when you are configuring the Access Token verification. For Signing Algorithm, select RS256.

Create API

Add API Authorization

To restrict access to the resources served by your API, check the incoming requests for valid authorization information. The authorization information is stored in the Access Token created for the user and needs to be sent in the Authorization header. To see if the token is valid, check it against the JSON Web Key Set (JWKS) for your Auth0 account. To learn more about validating Access Tokens, read the Verify Access Tokens tutorial.

This guide shows you how to validate the token using the jwt-express middleware and how to check for appropriate scopes with the express-jwt-authz middleware. If the token is not valid or does not have the required scopes, the user gets a 401 Authorization error when they try to access the endpoints.

Install the Dependencies

To verify incoming JWTs, you can use the express-jwt package.

To get your Auth0 public key and complete the verification process, you can use the jwks-rsa library with the package.

To add the authorization middleware to your endpoints, you can use the express-jwt-authz library.

Install these libraries with npm.

npm install --save express-jwt jwks-rsa express-jwt-authz

Configure the Middleware

By default, your API uses RS256 as the algorithm for signing tokens. Since RS256 uses a private/public keypair, it verifies the tokens against the public key for your Auth0 account. You can access this public key here.

We recommend using the default RS256 signing algorithm for your API. If you need to use the HS256 algorithm, see the HS256 integration sample.

Configure the express-jwt middleware so it uses the remote JWKS for your Auth0 account.

// server.js

const express = require('express');
const app = express();
const jwt = require('express-jwt');
const jwtAuthz = require('express-jwt-authz');
const jwksRsa = require('jwks-rsa');

// Authentication middleware. When used, the
// Access Token must exist and be verified against
// the Auth0 JSON Web Key Set
const checkJwt = jwt({
  // Dynamically provide a signing key
  // based on the kid in the header and 
  // the signing keys provided by the JWKS endpoint.
  secret: jwksRsa.expressJwtSecret({
    cache: true,
    rateLimit: true,
    jwksRequestsPerMinute: 5,
    jwksUri: `https://YOUR_AUTH0_DOMAIN/.well-known/jwks.json`
  }),

  // Validate the audience and the issuer.
  audience: '{YOUR_API_IDENTIFIER}',
  issuer: `https://YOUR_AUTH0_DOMAIN/`,
  algorithms: ['RS256']
});

Configure the Scopes

The checkJwt middleware shown above checks if the user's Access Token included in the request is valid. The middleware doesn't check if the token has the sufficient scope to access the requested resources.

Scopes let you define which resources can be accessed by the user with a given Access Token. For example, you might choose to give the read access to the messages resource if a user has the manager access level, and a write access to that resource if they have the administrator access level.

To configure scopes, in your Auth0 dashboard, in the APIs section, click the Scopes tab. Configure the scopes you need.

Configure Scopes

This example uses the read:messages scope.

Protect Individual Endpoints

To protect an individual route that requires a valid JWT, configure the route with the checkJwt express-jwt middleware.

// server.js

// This route doesn't need authentication
app.get('/api/public', function(req, res) {
  res.json({
    message: 'Hello from a public endpoint! You don\'t need to be authenticated to see this.'
  });
});

// This route need authentication
app.get('/api/private', checkJwt, function(req, res) {
  res.json({
    message: 'Hello from a private endpoint! You need to be authenticated to see this.'
  });
});

You can configure individual routes to look for a particular scope. To achieve that, set up another middleware with the express-jwt-authz package. Provide an array of the required scopes and apply the middleware to any routes you want to add authorization to.

Pass the checkJwt and checkScopes middlewares to the route you want to protect.

// server.js

const checkScopes = jwtAuthz([ 'read:messages' ]);

app.get('/api/private-scoped', checkJwt, checkScopes, function(req, res) {
  res.json({
    message: 'Hello from a private endpoint! You need to be authenticated and have a scope of read:messages to see this.'
  });
});

In this configuration, only the Access Tokens with the read:messages scope can access the endpoint.

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