private function timingSafeEquals($safeString, $userString)
{
if (function_exists('hash_equals')) {
return hash_equals($safeString, $userString);
}
$safeLen = strlen($safeString);
$userLen = strlen($userString);
if ($userLen != $safeLen) {
return false;
}
$result = 0;
for ($i = 0; $i < $userLen; ++$i) {
$result |= ord($safeString[$i]) ^ ord($userString[$i]);
}
// They are only identical strings if $result is exactly 0...
return $result === 0;
}