Decrypt TrueCrypt containers using dm-crypt

Question

Is it possible to decrypt TrueCrypt containers using dm-crypt?

I have some container files created with TrueCrypt and I just wanted to know if it's possible to decrypt them using dm-crypt so I can stop using TrueCrypt and use something more opensource like dm-crypt.

Solution

Yes you can do that. I use an external harddrive and mount it on my Ubuntu installations with cryptsetup/dm-crypt. But you need to update your cryptsetup packages to version 1.6 to get this functionality. I used this PPA on older Ubuntu releases.

Mounting a container is no different from mounting an encrypted partition as one would expect:

$ sudo cryptsetup tcryptOpen testcontainer.tc testcontainer

Now a new disk shows up in Nautilus or the launcher and you can mount it via Nautilus or terminal if you like. I mounted the container via Nautilus.

$ mount | grep testcontainer
/dev/mapper/testcontainer on /media/livewire/F29F-27D2 type vfat (rw,nosuid,nodev,uid=1000,gid=1000,shortname=mixed,dmask=0077,utf8=1,showexec,flush,uhelper=udisks2)

Don't forget to unmount the filesystem and the container itself after unmounting the filesystem:

$ sudo cryptsetup tcryptClose /dev/mapper/testcontainer

While a GUI only solution to mount such containers and partitions the same way you can mount LUKS partitions would be more comfortable, it is currently not possible as it seems.

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Automounting via pam_mount also seems to be not possible at the moment.

Comments

[Csabi Vidó]

I don't know of a Windows program that can read LUKS partitions/containers. So compatibility to Windows might be the reason?

[oshirowanen]

Doesn't seem to work for me. sudo cryptsetup tcryptOpen testcontainer.tc testcontainer give me cryptsetup: Unknown action.

[Csabi Vidó]

@oshirowanen That sounds like you're using an older version. You need to upgrade the package (via the PPA I mentioned) if you use an older release than trusy.

[oshirowanen]

Looks like I have cryptsetup 1.4.1 installed. Is that version too old?

[Csabi Vidó]

Yes, you need version 1.6 at least. Really.

[Tarik]

I need the solution to decrypt my truecrypt volumes and transfer them elsewhere. As such, the question is pertinent.