WindowsLiveLogin::signToken

function signToken($token, $signkey=null)
{
	if (!$signkey) {
		$signkey = $this->_signkey;
	}
	if (!$signkey) {
		$this->fatal("Error: signToken: Secret key was not set. Aborting.");
	}

	if (!$token) {
		$this->debug("Attempted to sign null token.");
		return;
	}

	return hash_hmac("sha256", $token, $signkey, true);
}