How do I back up encrypted data?
Hi, everyone. Leo Notenboom
here for askleo.com. This is one of those not so common,
not so obvious, but important questions that people should be asking.
I do get asked occasionally,
but it actually raises a very interesting point to make sure that when
you're backing up your data, if it happens to be encrypted,
you're backing it up in such a way that you are increasing the probability
that you'll actually be able to access the backup if you ever need it.
Here's the issue.
You've got some encrypted data.
Let's say that you've got either like a passwordprotected word document
which encrypts the contents, or you've got a password protected zip file.
Same idea.
The contents of that zip file is encrypted.
Maybe you have a Veracript volume,
a file on your system that is a Veracript volume that by definition is encrypted.
Perhaps you have a collection of files
encrypted by utilities like Boxcryptor or Cryptomater.
Perhaps you have a file that's been
encrypted using PGP or GPG encryption, public key cryptography.
Or perhaps you have a system that's been protected with whole disk encryption.
The common approach for backing these
files up, with the exception of the last one, is to back up the file,
is to back up the thing that I just talked about, the encrypted file.
So if you've got, say,
ImportantDocuments.Zip that happens to be a password protected zip file,
you back up ImportantDocuments.zip, password protection and all. That's.
Good.
Don't get me wrong, I'm thrilled that you're backing up,
but there's risk involved, perhaps risk that needn't be involved.
The issue is that encryption can fail,
and I mean that in any of several different ways.
The most common scenario, and I think the one that's easiest
to relate to is let's say ten years ago you backed up
ImportantDocuments zip and it's password protected.
Now here we are today.
You need something out of that file, but you can't remember the password.
If you can't remember the password well, you might as well have thrown the file
away ten years ago because you're not going to be able to get at its contents.
Another scenario is that occasionally
encryption algorithms are, I'll call them fragile in the sense that
usually if you've got an unencrypted file on your disk and something happens
to the disk, maybe you get a bad sector on the disk.
You can recover everything on either side of that bad sector, right?
You might get a little bit of noise
in the middle of your file, but you've got the beginning and you've got the end.
You've got the majority of your data.
Even if there's just one little thing wrong somewhere in the middle of the file,
if the file's been encrypted, that's not necessarily the case.
It is possible,
depending on the encryption that's been used, that the slightest error anywhere
in the file can render the entire file undecryptable.
In other words, you can't decrypt it because there's this
tiny little error in some random place in the file.
Again, if that happens and you can't decrypt the file, you've lost it.
You might as well have thrown it away when
you first created it, because this encrypted backup that maybe
has a bad sector in it somewhere can't be decrypted.
So what's the solution for these kinds of scenarios?
There are other scenarios, but those are probably the easiest to conceive of.
So what's the solution?
Well, the solution is somewhat obvious.
Backup the data in its unencrypted form.
So, for example, save a copy of that Word document without a password.
Save a copy of that zip file without a password.
Copy the files out of your VeraCrypt volume and store them separately.
Unencrypted.
Save unencrypted copies of the files that you place in boxcryptor or cryptomator.
Save unencrypted copies of the files
that you might encrypt using PGP or GPG public Key Encryption.
The bottom line here is save the unencrypted files.
Now, if you're using whole disk
encryption, this actually tends to get a little bit easier because most
of the techniques that you might use to back up a file if your hard disk is
encrypted, naturally back up the unencrypted form.
Make sure to check.
Make sure you understand how your backup tool works.
But for example, if you've got whole disk encryption and you back up files simply
by copying them somewhere else, those copies are not encrypted.
Whole disk encryption is only about the disk.
As soon as you copy things off of the disk, they're in their unencrypted form.
So you've got your unencrypted files, but you encrypted them for a reason.
Now you've got these unencrypted files lying around as backups.
That seems less than secure.
Okay, but that's also solved relatively.
Simply secure them some other way.
For example, if you've now copied all
of these important files in their unencrypted form to an external hard disk,
maybe lock that in a safe, maybe secure that information some other way.
The approach that I tend to take is to instead of physically moving things
around like that, I'll actually encrypt things some other way.
I'll give you an example.
I use Boxcrypter, and I have a backup task that goes through and makes an encrypted
zip file of the contents of the box crypto files.
What that means is all of the things
that have been encrypted by Boxcryptor are read in their unencrypted form,
placed into a zip file, and then password protected in that zip file.
In a sense, you're right.
I've got encrypted files over here.
Aren't they both at risk?
They are, but the risk has been spread.
The chances of losing both the box scripter access and the zip file access
at the same time, which is what you care about.
It's very, very small.
You'll either remember or have
the password to the zip file, or you'll remember or have access to your
Boxcryptor account or the recovery information there.
The idea here is not to throw around a lot
of secure files and store them in an unsecure way.
The idea here is to spread the risk,
to basically reduce the risk of any one kind of failure causing you a problem
by using a different form of protection for your backup copy.
The simplest could very well be if you're using an image backup program.
Remember, it's going to back up
the unencrypted version of everything on your hard disk.
Throw a password on that backup.
That way it's encrypted separately differently by the backup software and not
the hard disk encryption software, but it's secure at a minimum.
I don't necessarily want to say these are the techniques you should use because it
will depend dramatically on your own specific situation, your own needs,
how you back up, what tools you have available, and so on.
But what I want you to do is at least consider this scenario.
Take that example that I started
with of a file that you encrypted ten years ago and have forgotten the password.
How would you protect yourself from that?
What are the tools and techniques that you
might put into place to make sure that if that ever happens, you're safe?
At least consider the scenario.
You may decide that backing up your
encrypted data in its encrypted form is the right thing to do.
That's okay.
That might very well be the right thing
to do, but at least make sure you understand the ramifications of doing so.
I hope that's helpful.
I hope it gives you a little bit of something to think about.
For comments, for updates, for related links and more, visit askleo.com/43760.
I'm Leo Notenboom.
This is askleo.com. Thanks for watching.