PHP API Authentication

Sample Project

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

System Requirements
  • PHP v5
  • Composer 1.0
Show requirements

To restrict access to the resources served by your API, a check needs to be made to determine whether the incoming request contains valid authorization information. There are various methods for including authorization information in a request, but for integration with Auth0, your API needs to check for a valid JSON Web Token (JWT). When users log into your application, they will receive an id_token and an access_token which are both JWTs. The specific JWT that needs to be sent to your API is the access_token.

This sample demonstrates how to check for a JWT in the Authorization header of an incoming HTTP request and verify that it is valid. The validity check is done in the JWTVerifier class from the auth0-PHP library which can be applied to any endpoints you wish to protect. If the token is valid, the resources which are served by the endpoint can be released, otherwise a 401 Authorization error will be returned.

Install the Dependencies

The auth0-PHP library and its JWTVerifier class can be used to verify incoming JWTs. The router library can be used to create simple routes. Install the libraries with composer.

composer require bramus/router:dev-master auth0/auth0-php:~5.0

Configuration

By default, your API will be set up to use RS256 as the algorithm for signing tokens. Since RS256 works by using a private/public keypair, tokens can be verified against the public key for your Auth0 account. This public key is accessible at https://YOUR_AUTH0_DOMAIN/.well-known/jwks.json.

It is highly recommended that you use the default signing algorithm of RS256 for your API. If you do require HS256 as the algorithm, see the HS256 integration sample.

Create an instance of JWTVerifier and pass your API identifier to valid_audiences and your Auth0 domain to authorized_iss. You can also create a function which will be called to return a message when a request is made to a protected endpoint.

// src/Main.php

<?php

namespace App;

use Auth0\SDK\JWTVerifier;

class Main {

  protected $token;
  protected $tokenInfo;

  public function setCurrentToken($token) {

      try {
        $verifier = new JWTVerifier([
          'supported_algs' => ['RS256'],
          'valid_audiences' => ['{YOUR_API_IDENTIFIER}'],
          'authorized_iss' => ['https://YOUR_AUTH0_DOMAIN/']
        ]);

        $this->token = $token;
        $this->tokenInfo = $verifier->verifyAndDecode($token);
      }
      catch(\Auth0\SDK\Exception\CoreException $e) {
        throw $e;
      }
  }

  public function privatePing() {
      return array(
          "status" => "ok",
          "message" => "Hello from a private endpoint! You DO need to be authenticated to see this."
      );
  }

}

Configure Authenticated Routes

The before hook from the router package can be used to configure which routes are to be protected. For example, you may wish to protect all routes under a URL of /api/private.

// index.php

// ...
// Require composer autoloader
require __DIR__ . '/vendor/autoload.php';

// Read .env
try {
  $dotenv = new Dotenv\Dotenv(__DIR__);
  $dotenv->load();
} catch(InvalidArgumentException $ex) {
  // Ignore if no dotenv
}

$app = new \App\Main();

// Create Router instance
$router = new \Bramus\Router\Router();

// Activate CORS
function sendCorsHeaders() {
  header("Access-Control-Allow-Origin: *");
  header("Access-Control-Allow-Headers: Authorization");
  header("Access-Control-Allow-Methods: GET,HEAD,PUT,PATCH,POST,DELETE");
}

$router->options('/.*', function() {
    sendCorsHeaders();
});

sendCorsHeaders();

// Check JWT on /secured routes
$router->before('GET', '/api/private/.*', function() use ($app) {

  $requestHeaders = apache_request_headers();

  if (!isset($requestHeaders['authorization']) && !isset($requestHeaders['Authorization'])) {
      header('HTTP/1.0 401 Unauthorized');
      echo "No token provided.";
      exit();
  }

  $authorizationHeader = isset($requestHeaders['authorization']) ? $requestHeaders['authorization'] : $requestHeaders['Authorization'];

  if ($authorizationHeader == null) {
    header('HTTP/1.0 401 Unauthorized');
    echo "No authorization header sent";
    exit();
  }

  $authorizationHeader = str_replace('bearer ', '', $authorizationHeader);
  $token = str_replace('Bearer ', '', $authorizationHeader);

  try {
      $app->setCurrentToken($token);
  }
  catch(\Auth0\SDK\Exception\CoreException $e) {
    header('HTTP/1.0 401 Unauthorized');
    echo $e;
    exit();
  }

});

With this configuration, any time an endpoint which includes /api/private is reached, a valid JWT access_token will be required before the resource can be released. With this in place, private routes can be defined.

// index.php

$router->get('/api/private/ping', function() use ($app){
    echo json_encode($app->privatePing());
});
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