Added suport to mcrypt and openssl

src/Redsys/Tpv/Signature.php

@@ -49,13 +49,29 @@ private static function calculate($prefix, array $fields, array $values, $key)
     }
 
     private static function encrypt3DES($message, $key)
+    {
+        if (function_exists('openssl_encrypt')) {
+            return self::encrypt3DESOpenSSL($message, $key);
+        }
+
+        return self::encrypt3DESMcrypt($message, $key);
+    }
+
+    private static function encrypt3DESOpenSSL($message, $key)
     {
         $l = ceil(strlen($message) / 8) * 8;
         $message = $message.str_repeat("\0", $l - strlen($message));
 
         return substr(openssl_encrypt($message, 'des-ede3-cbc', $key, OPENSSL_RAW_DATA, "\0\0\0\0\0\0\0\0"), 0, $l);
     }
 
+    private static function encrypt3DESMcrypt($message, $key)
+    {
+        $iv = implode(array_map('chr', array(0, 0, 0, 0, 0, 0, 0, 0)));
+
+        return mcrypt_encrypt(MCRYPT_3DES, $key, $message, MCRYPT_MODE_CBC, $iv);
+    }
+
     private static function encryptKey($order, $key)
     {
         return self::encrypt3DES($order, base64_decode($key));