the whole shebang

vendor/symfony/http-kernel/Symfony/Component/HttpKernel/UriSigner.php

@@ -0,0 +1,72 @@
+<?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)));
+    }
+}