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Old 07-24-2007, 02:03 AM   #1
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Registered: Apr 2007
Posts: 24

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Encrypted incremental backups?

Hi all,

I'm using rsync for performing daily incremental backups of my data as described on this page: .

rm -rf backup.3
mv backup.2 backup.3
mv backup.1 backup.2
cp -al backup.0 backup.1
rsync -a --delete source_directory/ backup.0/

I face the problem that the backup disk is insecure, i.e., everybody in our group can access it.

Currently I decrypt the backup files before running the backup and encrypt them again afterwards. This is both insecure and inefficient.

Is ist possible, e.g., through pipes and programs like openssl / gnupg to encrypt / decrypt the backup files "on the fly"? I'm looking for a more integrated (and therefore more secure) solution than what I do currently.

What do you do to perform secure incremental backups?

Many thanks,
Old 07-24-2007, 07:59 AM   #2
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Location: Massachusetts, USA
Distribution: Ubuntu 10.04 and CentOS 5.5
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I would use a separate disk partition to store the backups and encrypt that partition. In fact, that's what I actually do. The nice thing about encrypting the entire disk partition is that you don't have decrypted files on disk.

You can use the built in encryption in Linux but I have found that this can be a problem. Linux distributions do not all support the same encryption algorithms. I started using True Crypt a couple of years ago. Now it doesn't matter what the Linux distribution that I'm using supports natively. True Crypt provides a common encryption platform whether you change Linux distributions or if you are using Linux and Windows to read the same disk partition.

Look for the truecrypt tag on this web site (LQ) for more information about using True Crypt.

Last edited by stress_junkie; 07-24-2007 at 08:02 AM.
Old 07-24-2007, 08:30 AM   #3
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Many thanks. In the meantime I found a program called "duplicate" which fullfills my requirements. It combine rsync with gnupg and seems to work well for encrypted incremental updates.

All the best,
Old 07-25-2007, 06:57 AM   #4
Registered: Apr 2006
Location: Sweden
Distribution: CentOS, RHEL, SourceMage, OpenBSD
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Just for the record, there is actually a program for windows that can read dm-crypt volumes. It's called FreeOTFE and you can get it here:

I've tried it and it works but read the documentation here:


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