PHP API: Authentication

Gravatar for josh.cunningham@auth0.com
By Josh Cunningham
Auth0

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

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 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 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.

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;
    }
  }

  // This endpoint doesn't need authentication
  public function publicEndpoint() {
    return array(
      "status" => "ok",
      "message" => "Hello from a public endpoint! You don't need to be authenticated to see this."
    );
  }

  public function privateEndpoint() {
    return array(
      "status" => "ok",
      "message" => "Hello from a private endpoint! You 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 private 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');
    header('Content-Type: application/json; charset=utf-8');
    echo json_encode(array("message" => "No token provided."));
    exit();
  }

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

  if ($authorizationHeader == null) {
    header('HTTP/1.0 401 Unauthorized');
    header('Content-Type: application/json; charset=utf-8');
    echo json_encode(array("message" => "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');
    header('Content-Type: application/json; charset=utf-8');
    echo json_encode(array("message" => $e->getMessage()));
    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

// This route doesn't need authentication
$router->get('/api/public', function() use ($app){
  header('Content-Type: application/json; charset=utf-8');
  echo json_encode($app->publicEndpoint());
});

$router->get('/api/private', function() use ($app){
  header('Content-Type: application/json; charset=utf-8');
  echo json_encode($app->privateEndpoint());
});

Configure the Scopes

To add authorization you need to define the method checkScope to check for a particular scope in the access_token.

// src/Main.php

//..

public function checkScope($scope){
  if ($this->tokenInfo){
    $scopes = explode(" ", $this->tokenInfo->scope);
    foreach ($scopes as $s){
      if ($s === $scope)
        return true;
    }
  }

  return false;
}

// ...

public function privateScopedEndpoint() {
  return array(
    "status" => "ok",
    "message" => "Hello from a private endpoint! You need to be authenticated and have a scope of read:messages to see this."
  );
}

The function privateScopedEndpoint will return the message when a request is made from a protected endpoint, and the access_token has a scope of read:messages.

Add a before hook to the router to configure routes that require the scope of read:messages.

// index.php

// Check for read:messages scope
$router->before('GET', '/api/private-scoped', function() use ($app) {
  if (!$app->checkScope('read:messages')){
    header('HTTP/1.0 403 forbidden');
    header('Content-Type: application/json; charset=utf-8');
    echo json_encode(array("message" => "Insufficient scope."));
    exit();
  }
});

// ...

$router->get('/api/private-scoped', function() use ($app){
  header('Content-Type: application/json; charset=utf-8');
  echo json_encode($app->privateScopedEndpoint());
});

The route /api/private-scoped will be accessible only if has a valid access_token with the scope read:messages.

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