Node (Express) API: Authorization

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Node (Express) API: Authorization

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By Andres Aguiar
Auth0

This tutorial demonstrates how to add authentication and authorization to an Express.js API. We recommend you to Log in to follow this quickstart with examples configured for your account.

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System requirements: express.js 4.4.0 | express-jwt 5.1.0 | express-jwt-authz 1.0.0

New to Auth? Learn How Auth0 works and read about API authorization.

Configure Auth0 APIs

Create an API

In the APIs section of the Auth0 dashboard, click Create API. Provide a name and an identifier for your API, for example https://quickstarts/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

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. The public key is in the JSON Web Key Set (JWKS) format, and can be accessed 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.

Define scopes

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

You can add the required scopes in the Scopes tab of the Auth0 Dashboard's APIs section.

Configure Scopes

This example uses the read:messages scope.

This example demonstrates:

  • How to check for a JSON Web Token (JWT) in the Authorization header of an incoming HTTP request.

  • How to check if the token is valid, using the JSON Web Key Set (JWKS) for your Auth0 account. To learn more about validating Access Tokens, read the Verify Access Tokens tutorial.

Validate Access Tokens

Install dependencies

This guide shows you how to validate the token using the express-jwt middleware and how to check for appropriate scopes with the express-jwt-authz middleware.

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

Install these libraries with npm.

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

Configure the middleware

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']
});

The checkJwt middleware shown above checks if the user's Access Token included in the request is valid. If the token is not valid, the user gets a 401 Authorization error when they try to access the endpoints. The middleware doesn't check if the token has the sufficient scope to access the requested resources.

Protect API Endpoints

The routes shown below are available for the following requests:

  • GET /api/public: available for non-authenticated requests
  • GET /api/private: available for authenticated requests containing an Access Token with no additional scopes
  • GET /api/private-scoped: available for authenticated requests containing an Access Token with the read:messages scope granted

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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