encryption and operating systems (two questions)

[Dan Lester]

I have a couple of puzzles, that maybe you can help me with. Not sure if these puzzles are related, or irrelevant to each other.

I have 2 10.9 Mac laptops, both using SuperDuper on one shared backup drive. That is, I use one volume for one machine, and another volume for the other. One of the 10.9s is encrypted. The other is not.

The first question is whether the SuperDuper backup of the encrypted Mac can itself be considered encrypted. That is, can anyone grab that backup drive and see all my data? This question comes up because I'm taking the encrypted machine on an overseas trip, and I'm wondering whether it is a security risk to take the backup drive along with it. The answer to that may be self evident, in that when that backup drive is plugged into the unencrypted Mac, I have no trouble seeing the backed up files from the encrypted one! I find that surprising, security-wise.

The second question is about file accessibility. When I plug that backup drive into a 10.10 iMac, I can't see the backup volumes stored on it. Well, I can see non-user pieces of the backup volume for the encrypted drive, but I can't see the backup volume of the unencrypted drive at all. Those volumes are fully visible on the 10.9 machines. What's going on? Are the Super Duper copies OS-specific? Such that you can only peruse them with the OS that made them?

Thank you for any illumination you can provide.

[dnanian]

1. If your source is encrypted with FDE (FV2), then the backup isn't encrypted unless you explicitly format the backup as encrypted and Smart Update to it.

2. I don't know why that would be. Are the volumes visible in Disk Utility?

[Dan Lester]

Thanks you. As to (1), that makes sense. I frankly forgot that one formatting option was encryption (I didn't set up the encryption on that machine), and it's great that Smart Update obeys that.

As to (2), I need to play around with it some more. I'm presuming that the SuperDuper backups are NOT OS-specific such that I should be able to extract files from a backup made with one OS by another OS. Right?

[dnanian]

SuperDuper! backups are copies of the source, written totally normally to OS-formatted drives in OS format. "Later" OS versions do make changes to HFS+/Mac OS Extended that aren't 100% compatible with "earlier" OS versions, but, in general, the files are just files, and if you could read from the original drive you'd be able to read from the copy.