Does anyone know how to encrypt an existing partition in linux while preserving its data

Question

If I have a partition like /dev/hd1 that is unencrypted and want it to be encrypted, but want to keep everything currently in that partition, how can I do that?

Answer 1

There does not seem to be an solution to do that in place. Truecrypt offers the system encryption only for windows, dm-crypt overwrites partitions. Your best bet would be to move everything from that partition into a backup with cp -a, create an encrypted partition with luks/dm-crypt and move everything back.

Answer 2

Actually you can convert from a plain filesystem partition to dm-crypt.

But it's risky and cumbersome.

There is an out-dated tutorial here: https://help.ubuntu.com/community/EncryptedFilesystemHowto7

Dm-crypt maps one block to one block, so in theory it is doable. Luks is a user-friendly container that uses dm-crypt inside it. A luks partition contains a header and a dm-crypt partition inside it, where the encrypted filesystem really lives.

Warnings:

1. If you choose to go Luks then your task is even harder, and you will need to know exactly how much ahead the dm-crypt data should be with respect to the begining of the official partition.

2. In any case, if your system crashes or halts during the procedure you loose your data

More references:

http://www.richardneill.org/a22p-mdk11-0.php#encrypt2

http://www.saout.de/tikiwiki/tiki-index.php?page=EncryptExistingDevice