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HappyDeveloper
Asked: 2012-06-06 15:33:07 +0800 CST

Does LUKS also encrypt free space?

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I have moved to Ubuntu 12 and chosen to use full disk encryption (encrypted LVM).

So now I'm wondering: should I shred (eg: with secure-delete package, srm) the free disk space to remove any remnant windows might have left?

Is free disk space treated any different?

luks disk-encryption

1 Answers

  1. The standard recommendation, is that you over-write a disk/volume with random data before you setup luks. The Ubuntu installer will even offer to do this for you if you select the Expert mode. I don't believe the latest version will do this by default though, but I haven't actually tried it. This is often skipped/ignored because the process will take a long time.

    But no, luks does not automatically fill or over-write blocks when it is setup.

    Using the psuedo random generator in badblocks (badblocks -c 10240 -wsvt random /dev/<device>)is usually considered good enough and suggested as a good method to wipe a volume by most LUKS guides and HOWTOs.

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