An implementation of the HTTP HMAC Spec in PHP that integrates with popular libraries such as Symfony and Guzzle.


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This library implements version 2.0 of the HTTP HMAC Spec to sign and verify RESTful Web API requests. It integrates with popular frameworks and libraries, like Symfony and Guzzle, and can be used on both the server and client.


Use Composer and add it as a dependency to your project's composer.json file:

    "require": {
        "acquia/http-hmac-php": "^5.0"

Please refer to Composer's documentation for more detailed installation and usage instructions.


Sign an API request sent via Guzzle

require_once 'vendor/autoload.php';

use Acquia\Hmac\Guzzle\HmacAuthMiddleware;
use Acquia\Hmac\Key;
use GuzzleHttp\Client;
use GuzzleHttp\HandlerStack;

// Create the HTTP HMAC key.
// A key consists of and ID and a Base64-encoded shared secret.
// Note: the API provider may have already encoded the secret. In this case, it should not be re-encoded.
$key_id = 'e7fe97fa-a0c8-4a42-ab8e-2c26d52df059';
$key_secret = base64_encode('secret');
$key = new Key($key_id, $key_secret);

// Optionally, you can provide additional headers when generating the signature.
// The header keys need to be provided to the middleware below.
$headers = [
    'X-Custom-1' => 'value1',
    'X-Custom-2' => 'value2',

// Specify the API's realm.
// Consult the API documentation for this value.
$realm = 'Acquia';

// Create a Guzzle middleware to handle authentication during all requests.
// Provide your key, realm and the names of any additional custom headers.
$middleware = new HmacAuthMiddleware($key, $realm, array_keys($headers));

// Register the middleware.
$stack = HandlerStack::create();

// Create a client.
$client = new Client([
    'handler' => $stack,

// Request.
try {
    $result = $client->get('', [
        'headers' => $headers,
} catch (ClientException $e) {
    print $e->getMessage();
    $response = $e->getResponse();
print $response->getBody();

Authenticate the request using PSR-7-compatible requests

use Acquia\Hmac\RequestAuthenticator;
use Acquia\Hmac\ResponseSigner;

// $keyLoader implements \Acquia\Hmac\KeyLoaderInterface
$authenticator = new RequestAuthenticator($keyLoader);

// $request implements PSR-7's \Psr\Http\Message\RequestInterface
// An exception will be thrown if it cannot authenticate.
$key = $authenticator->authenticate($request);

$signer = new ResponseSigner($key, $request);
$signedResponse = $signer->signResponse($response);

Authenticate using Symfony's Security component

In order to use the provided Symfony integration, you will need to include the following optional libraries in your project's composer.json

    "require": {
        "symfony/psr-http-message-bridge": "~0.1",
        "symfony/security": "~3.0",
        "zendframework/zend-diactoros": "~1.3.5"

Sample implementation:

# app/config/parameters.yml
   hmac_keys: {"key": "secret"}

# app/config/services.yml
        class: Acquia\Hmac\KeyLoader
            $keys: '%hmac_keys%'

        class: Acquia\Hmac\RequestAuthenticator
         - '@hmac.keyloader'
        public: false
        class: Acquia\Hmac\Symfony\HmacResponseListener
          - { name: kernel.event_listener, event: kernel.response, method: onKernelResponse }
        class: Acquia\Hmac\Symfony\HmacAuthenticationEntryPoint
        class: Acquia\Hmac\Symfony\HmacAuthenticationProvider
            - '@hmac.request.authenticator'
        public: false
        class: Acquia\Hmac\Symfony\HmacAuthenticationListener
        arguments: ['@security.token_storage', '@security.authentication.manager', '@hmac.entry-point']
        public: false

# app/config/security.yml
    # ...

            pattern:   ^/api/
            stateless: true
            hmac_auth: true
// src/AppBundle/AppBundle.php
namespace AppBundle;

use Acquia\Hmac\Symfony\HmacFactory;
use Symfony\Component\HttpKernel\Bundle\Bundle;
use Symfony\Component\DependencyInjection\ContainerBuilder;

class AppBundle extends Bundle
    public function build(ContainerBuilder $container)
        $extension = $container->getExtension('security');
        $extension->addSecurityListenerFactory(new HmacFactory());

PHPUnit testing a controller using HMAC HTTP authentication in Symfony:

  1. Add the service declaration:
# app/config/parameters_test.yml

        class: Acquia\Hmac\Test\Mocks\Symfony\HmacClient
        arguments: ['@kernel', '%test.client.parameters%', '@test.client.history', '@test.client.cookiejar']
// src/AppBundle/Tests/HmacTestCase.php

namespace MyApp\Bundle\AppBundle\Tests;

use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Bundle\FrameworkBundle\Client;
use Acquia\Hmac\Key;

class HmacTestCase extends WebTestCase
     * @var Client
    private $client;

    protected static function createClient(array $options = array(), array $server = array())
        $kernel = static::bootKernel($options);

        $client = $kernel->getContainer()->get('test.client.hmac');

        return $client;

    protected function setUp()
        $this->client = static::createClient();

        $this->client->setKey(new Key('my-key', 'my-not-really-secret'));

Contributing and Development

GNU Make and Composer are used to manage development dependencies and testing:

# Install depdendencies
make install

# Run test suite
make test

All code should adhere to the following standards:

Submit changes using GitHub's standard pull request workflow.