public function serializeToken(AuthToken $token)
  {
    $payload = $this->encrypter->encrypt(array(
      'id' => $token->getAuthIdentifier(),
      'key' => $token->getPublicKey())
    );

		$payload = str_replace(array('+', '/', '\r', '\n', '='), array('-', '_'), $payload);

    return $payload;
  }