如果用户来自特定网页，如何跳过.htaccess中的身份验证？

So I have multiple (sub)-domains. All of them link towards one server, but on different folders with different file structures. For example:

http://webapp1.example.com/  //Subdomains don't have https (no wildcard)
https://www.example.com/webapp_that_needs_https (some webapps are required to have https and therefore can't be on a subdomain)
http://webapp2.example.com/

Every webapp has its own .htpasswd-protection, this is the .htaccess-file:

# Password
AuthType Basic
AuthName "Password Protected Area"
AuthUserFile /www/serverid/webpages/webapp1/.htpasswd
Require valid-user

Now I want to make a webpage on a subdomain, that lists and links all of the webapps. This file should be password-protected as well. If the user navigates to one of the webapp-pages using this password-protected list, the htaccess-protection for the webapps should be skipped.

If the user skips the listing page and navigates directly to the webapp-domain, the password protection should appear as usual.

Is there any way to achieve this probably really uncommon feature?

I believe you can do this using an if directive. In your .htaccess you would use:

<if "%{HTTP_HOST} != 'example.com'">
    ....
</if>

So you would put the domain you want them to refer from in the if directive and if it does not match, then it runs the Auth Type. Leaving your final code with:

<if "%{HTTP_HOST} != 'example.com'">
    # Password
    AuthType Basic
    AuthName "Password Protected Area"
    AuthUserFile /www/serverid/webpages/webapp1/.htpasswd
    Require valid-user
</if>