How does that question relate to Firefox support?

Your options are limited in terms of choice and application. However, if you are willing to spend a few bucks, your best option is Folder Lock 7. The software has been around for a while and can create encrypted folders of up to 4 terabytes (guessing this should be more than enough for you?). Here is the link to folder lock: http://www.newsoftwares.net/folderlock/ Also, folder lock 7 has been rated the best encryption software, so you are killing two birds with one stone, check it out! http://encryption-software-review.toptenreviews.com/folder-lock-review.html