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[ Team LiB ]
Recipe 7.25 Encrypting Backups
7.25.1 Problem
You want to create an encrypted backup.
7.25.2 Solution
Method 1: Pipe through gpg.
• To write a tape:
$ tar cf - mydir | gpg -c | dd of=/dev/tape bs=10k
• To read a tape:
$ dd if=/dev/tape bs=10k | gpg --decrypt | tar xf -
• To write an encrypted backup of directory mydir onto a CD-ROM:
"docList">where SPEED and SCSIDEVICE
are specific to your system; see cdrecord(1).
Method 2: Encrypt files separately.
1. Make a new directory containing links to your original files:
$ cp -lr mydir newdir
2. In the new directory, encrypt each file, and remove the links to the unencrypted files:
$ find newdir -type f -exec gpg -e '{}' \; -exec rm '{}' \;
3. Back up the new directory with the encrypted data:
$ tar c newdir
7.25.3 Discussion
Method 1 produces a backup that may be considered fragile: one big encrypted file. If part of the backup gets
corrupted, you might be unable to decrypt any of it.
Method 2 avoids this problem. The cp -l option creates hard links, which can only be used within a single
filesystem. If you want the encrypted files on a separate filesystem, use symbolic links instead:
$ cp -sr /full/path/to/mydir newdir
$ find newdir -type l -exec gpg -e '{}' \; -exec rm '{}' \;
Note that a full, absolute pathname must be used for the original directory in this case.
gpg does not preserve the owner, group, permissions, or modification times of the files. To retain this
information in your backups, copy the attributes from the original files to the encrypted files, before the links
to the original files are deleted:
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