Can search engines see password protected pages?

In most of the cases Search engines are not different from regular users. Search engines cannot go anywhere that a regular user cannot go. If we have a password protected area on our website that cannot be accessed without a login and password then the search engines also cannot see it.

It isn't possible, Google or other search engines would not crawl password protected pages. Only web pages which are available public would be crawled and indexed.

No, Google cannot access password-protected pages. If you want to be extra certain the pages don't turn up in search, disallow the pages through your robots.