http://www.magnetforensics.com/decrypting-the-dropbox-filecache-dbx-file-new-free-tool/
I was looking to find out what the files were, why they are so large, do they need to be backed up, etc. And then, ran into a way to decrypt them.
Suggestions and opinions?
If you have access to the encrypted DropBox cache you likely also have access to the raw files themselves (via both DropBox and the File System) and also have the meta data stored elsewhere (e.g. filesystem, backups, restore points, et al).
The fact that DropBox even encrypts that is "cute." The fact they encrypt it using the LSASS makes it almost worth while (almost). But realistically there are very few scenarios outside of computer forensics where this kind of thing is useful to someone.
The reason it is useful to them is: They may not have a warrant for your DropBox (but do have your computer in their possession). The files are deleted locally but on DropBox, so they can leverage the cache to get a warrant for DropBox.
As a note tons of other stuff caches meta data within unencrypted SQLite databases such as Skype, Chrome, Firefox, Thunderbird, et al. It isn't a security issue there either as your user is meant to have access to this (just as with DropBox).
They are in ~ in a dir that is a .dir so hidden from 90% ( guessing ) of most casual DB users. If someone were to delete their home files, by putting them in the trash, they may think they deleted their DropBox data too, but they would be wrong.
It was that scenario I was concerted about, or at least, wanted to know more about so I could be sure to delete those files and know it is safe to do so, and won't harm the files stored in my DropBox on other machines, or in a recovery procedure.