Recently I have moved my wife from windows to OSX. She received my 'old' macbook pro and I received a new macbook pro. Because of this my wife and I have decided we wanted to improve our important documents backup process. Originally this process was that all important documents (tax and bank information, scanned documents such as titles, deeds, receipts, and insurance pictures) was copied on to a USB stick and placed in our fireproof safe, a second TrueCrypt encrypted disk was kept in my wife's purse. A 3rd copy was placed on my storage server. Mind you this is just for our most critical data. Other unimportant data such as movie backups, or music is simply stored on my file server using raid 5 and backed up to USB disk. We backup our family pictures the same way and also keep them on picasa.
Now that she is no longer using windows, we changed the method to as follows, a copy is placed on a USB stick in our fireproof safe. A copy is backed up by time machine. Another copy is automatically sent via ssh to my notebook and placed on my time machine (separate usb drives).
What we wanted to improve was the usb key in my wife's purse. This is to help us if say the fireproof safe was not fireproof and the house burned down. The idea was hopefully she will have her purse with her (and not be home). This is the weak link.
Because these files are way way less then 2 gig, my solution was to use DropBox. I know that DropBox uses 256 bit encryption, but I have no reason to trust they would never look at my data or have some exploit that lets people steal my data. The obvious solution is to make a sparse image (DMG file) that is encrypted. So I created a sparse image and set it's max size to 1.9g (to insure we never break the 2 gig free limit) and for security purposes I use AES-256 encryption on the image.
All has been well with this process, until my wife asked me what would happen if we did not have a mac and needed to get to the files. Say our house burned down with both macs inside and no one we know has a mac (which is true). How do we get the data from the dmg file.
A quick google shows there is a program called DMGExtractor that can read AES-128 encrypted dmg files, but it does not say it supports AES-256. So my question is does anyone know a program that can read AES-256 encrypted DMG sparse images on Linux or even Windows?
If such a program does not exist, do you think it would be wise to instead use a TrueCrypt container for this purpose? Do you have any better suggestions for this backup scheme? We are trying to keep the cost as close to free as possible."