OK I see. I have a dropbox account and have never had to use...

OK I see. I have a dropbox account and have never had to use even a password or an encryption key and still don't but it may have different features when you pay for a dropbox service. I use the free part and only use it to share files between my devices and sometimes with other people. From what I read and see with Covata's SafeShare you use encryption keys so that an unauthorised user cannot get to your files.