UriSigner.php

<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace Symfony\Component\HttpKernel;


/**
 * Signs URIs.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class UriSigner {
  private $secret;

  /**
   * Constructor.
   *
   * @param string $secret A secret
   */
  public function __construct($secret) {
    $this->secret = $secret;
  }

  /**
   * Signs a URI.
   *
   * The given URI is signed by adding a _hash query string parameter
   * which value depends on the URI and the secret.
   *
   * @param string $uri A URI to sign
   *
   * @return string The signed URI
   */
  public function sign($uri) {
    return $uri . (false === strpos($uri, '?') ? '?' : '&') . '_hash=' . $this
      ->computeHash($uri);
  }

  /**
   * Checks that a URI contains the correct hash.
   *
   * The _hash query string parameter must be the last one
   * (as it is generated that way by the sign() method, it should
   * never be a problem).
   *
   * @param string $uri A signed URI
   *
   * @return Boolean True if the URI is signed correctly, false otherwise
   */
  public function check($uri) {
    if (!preg_match('/^(.*)(?:\\?|&)_hash=(.+?)$/', $uri, $matches)) {
      return false;
    }
    return $this
      ->computeHash($matches[1]) === $matches[2];
  }
  private function computeHash($uri) {
    return urlencode(base64_encode(hash_hmac('sha1', $uri, $this->secret, true)));
  }

}