Passwording Forums/Threads - What are my options?
 

I am intending to launch a forum which will discuss certain products (mainly books). I only want owners of the product to be able to read and participate in such discussions.

The ideal way for this to happen would be for a user to be prompted to enter "the first word from page 5" as the password when they try to access the forum for a particular product. Even more ideally they should only have to do this once.

The process of authorising users access to such areas needs to be automated, as potentially there will be 100s of different products, 1000s of members and those members will be buying various products all the time.

How would you go about doing this? Is there functionality already built into vbulletin that could facilitate it?

Any advice much appreciated.
Thanks.