Signer::getKey

protected function getKey($salt = null)
{
	if ($salt !== null && !preg_match('#^[a-zA-Z0-9_.-]{3,50}$#D', $salt))
		throw new BadSignatureException('Malformed salt, only [a-zA-Z0-9_.-]{3,50} characters are acceptable');

	if ($this->key !== null)
		$key = $this->key;
	else
		$key = $this->getDefaultKey();

	return strval($salt).$key;
}