authentication - How would I require a password for all files except one using .htaccess? -

I have a new website on which I am working that the customer wants to keep a secret, but at the same time, I I want to make a page under construction with some information, I would like to do everything except the index / want that the user / password - index.html will be available to everyone.

I have the following, but I'm not sure what to add to me:

  AuthName "restricted area" AuthType Basic AuthUserFile /path/to/file/.htpasswd AuthGroupFile / dev / null Valid-user is required  

There are also many files and potentially new files "This user needs a password / user for this set".

I think there is something similar in this:

  & lt; Files index.html & gt; Decline order, allow all & lt; / Files & gt;  

But I'm pretty sure how.

  AUTHName "restricted area" operation default AuthUserFile /path/to/file/.htpasswd AuthGroupFile / Dev / null & lt; Files "*" & gt; Valid-user requirement & lt; / Files & gt; & Lt; Files "index.html" & gt; Allow anyone from any & lt; / Files & gt;