[dm-crypt] Truecrypt system partition support

Milan Broz gmazyland at gmail.com
Sun Jun 23 17:33:13 CEST 2013


Hi,

On 21.6.2013 15:58, Jan Janssen wrote:
> On Thursday 20 June 2013 18:50:10 Milan Broz wrote:
>> Hi,
>>
>> well, you are probably the first real user I know about who tried system
>> encryption truecrypt mapping :) So it is quite possible there are some
>> problems.
> 
> That's probably because it's not well advertised. I found out about it by
> accident and wanted to give it a try.

Yes, that's true.

The shared device for system encryption is fixed in devel git
http://code.google.com/p/cryptsetup/source/detail?r=a36de633d50d1e047cf5c0c3bc5e4d16a411fb62#

Please let me know if there is any other problem.

> Also, it took me a while to figure out (thanks to the manpage) that you have
> to use /dev/sda to open in system mode. It would be useful if cryptsetup
> could either figure out where to look for its offset from /dev/sda2 like
> the "real" truecrypt does or at least give a hint that in system mode the
> drive should be used instead of the partition.

Well, the Truecrypt header is not on partition for system encryption, it
is outside of it, that's why it is done this way.

Anyway, I added hint as well if header is not detected
http://code.google.com/p/cryptsetup/source/detail?r=42b0ab437a6ef332dd33e1eda144d2c3d9a70d23

I know automatic detection is better (and will work on Windows) but with Linux,
there can be virtualized systems where partition is used as "whole device"
for some Windows VM.
Also in some cases (LVM) it can be tricky to detect partitions and top level devices.

Also partition can be in different (security) context than the whole device.

Thanks!
Milan


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