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From: avlee on 14 Sep 2008 04:21
Hello

I have partistion encrypted with cryptoloop.
But after upgrading to new gentoo - it does not support it any more.
When i try to mount:

arrakis ~ # mount /dev/md7
Password:
ioctl: LOOP_SET_STATUS: No such file or directory

(i did not touch kernel during upgrade, so i have everything what was
needed)
I want to migrate to dm-crypt.
The question is how can i do it without loosing data on cryptoloop
partitions ?

If i: cryptsetup -y create mycrypt /dev/md7
and provide the same password will it see old partition ? (is it
"compatibile" with cryptoloop ?)

Thanx
From: Gregory Shearman on 14 Sep 2008 04:29
On 2008-09-14, avlee <teknet8(a)gazeta.pl> wrote:
> Hello
>
> I have partistion encrypted with cryptoloop.
> But after upgrading to new gentoo - it does not support it any more.
> When i try to mount:
>
> arrakis ~ # mount /dev/md7
> Password:
> ioctl: LOOP_SET_STATUS: No such file or directory
>
> (i did not touch kernel during upgrade, so i have everything what was
> needed)
> I want to migrate to dm-crypt.
> The question is how can i do it without loosing data on cryptoloop
> partitions ?
>
> If i: cryptsetup -y create mycrypt /dev/md7
> and provide the same password will it see old partition ? (is it
> "compatibile" with cryptoloop ?)

Have you tried installing loop-aes?

--
Regards,

Gregory.
Gentoo Linux - Penguin Power
From: avlee on 14 Sep 2008 04:44
> On 2008-09-14, avlee <teknet8(a)gazeta.pl> wrote:
>> Hello
>>
>> I have partistion encrypted with cryptoloop.
>> But after upgrading to new gentoo - it does not support it any more.
>> When i try to mount:
>>
>> arrakis ~ # mount /dev/md7
>> Password:
>> ioctl: LOOP_SET_STATUS: No such file or directory
>>
>> (i did not touch kernel during upgrade, so i have everything what was
>> needed)
>> I want to migrate to dm-crypt.
>> The question is how can i do it without loosing data on cryptoloop
>> partitions ?
>>
>> If i: cryptsetup -y create mycrypt /dev/md7
>> and provide the same password will it see old partition ? (is it
>> "compatibile" with cryptoloop ?)
>
> Have you tried installing loop-aes?
>


no, i did not. i want to aviod it. I try to find any bootable linux cd
which support cryptoloop with AES256.
Unfortunately gentoo install cd only supports AES128. Could you recoomend
any distribution which support cryptoloop with AES256 ?

Thanx
From: Douglas Mayne on 14 Sep 2008 11:01
On Sun, 14 Sep 2008 10:21:44 +0200, avlee wrote:

> Hello
>
> I have partistion encrypted with cryptoloop.
> But after upgrading to new gentoo - it does not support it any more.
> When i try to mount:
>
> arrakis ~ # mount /dev/md7
> Password:
> ioctl: LOOP_SET_STATUS: No such file or directory
>
> (i did not touch kernel during upgrade, so i have everything what was
> needed)
> I want to migrate to dm-crypt.
> The question is how can i do it without loosing data on cryptoloop
> partitions ?
>
> If i: cryptsetup -y create mycrypt /dev/md7
> and provide the same password will it see old partition ? (is it
> "compatibile" with cryptoloop ?)
>
AFAIK, cryptsetup is backward compatible with the older cryptoloop. Be
aware, you must use "plain" hashing for the key (-h plain).

The following should achieve equivalent results. YMMV (all ciphers and
cases not tested).

# losetup -e serpent /dev/loop0 /dev/hdx1

# cryptsetup -h plain -c serpent create hdx1 /dev/hdx1
>
> Thanx
>
Note: comment inline.

You should look in your kernel's configuration to make sure you have
support for both cryptoloop and for device mapper targets. For example,

$ cat /proc/config.gz | gzip -cd | grep CRYPTOLOOP
$ cat /proc/config.gz | gzip -cd | grep DM_

These kernel modules can be built-in, modular, or not included. If they
are modules, you need to "modprobe" them first.

# modprobe cryptoloop
# modprobe dm-crypt

Here are a few extra notes for your consideration:
1. If you are converting your partitions to use new keys, then some key
hashing function should be selected. "Plain" is usually not ideal. This is
specified with the -h parameter to cryptsetup.

2. New encryption ciphering techniques have been added which use better
IV hashing functions. For example, aes-cbc-essiv:sha256 is one type that
has been added to offer similar functionality to loop-aes. YMMV.

3. Low-level assembly routines have been added to the kernel for added
performance to aes ciphering. Its performance is on par with serpent, now.
YMMV.

--
Douglas Mayne



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