[TYPO3] password protect a single page?

[Bing Du]

Hi,

Typo3 V4.0.4.

We use single sign on here.  People within our organization are
authenticated somewhere else and redirect back if authentication succeeds.
 One customer now requests to protect one of their pages using some code,
username is not necessary.  The page is hidden in menu in the page tree. 
The page should be visible to those around the world who know the code. 
Personally, I don't think adding code would do any good in protecting the
page.  But I can create a new page that maybe just has a form asking
people to enter code, then write up some PHP code to show  the page if the
code matches or reject if the code doesn't match.  How do other people
handle such kind of situations?  Any better ideas?

Thanks in advance,

Bing