[dm-crypt] Migrating from loop AES to dm-crypt

Milan Broz gmazyland at gmail.com
Tue Sep 18 09:47:01 CEST 2012


On 09/18/2012 09:16 AM, Ludwig Nussel wrote:
> Nick Battle wrote:
>> I've just upgraded from openSUSE 12.1 to 12.2. I find that the latest version of
>> mount and losetup do not have the file encryption options they used to, since
>> everyone should have migrated to dm-crypt. The trouble is, I now have some
>> encrypted backup volumes that I cannot read!
>>
>> I used to mount the archives with:
>>
>> 	mount ... -o loop,phash=sha256,encryption=aes128
>>
>> It looks like I should be using the loopaesOpen option to cryptsetup to mount
>> these now, but I cannot find a combination of options that works. I'm trying the
>> following:
>>
>> cryptsetup loopaesOpen <device> <name> --key-file pp --key-size 128 --hash
>> sha256 -c aes-cbc-plain
> 
> IIRC loopaesOpen is for the multi key mode of newer loop aes. The crypto
> patches we had in openSUSE were based on a loop aes from a decade ago
> which didn't do anything fancy yet. So standard 'create' should work
> just fine with the parameters you figured out already. See also
> http://en.opensuse.org/SDB:Encrypted_filesystems#aes_cryptoloop_image

loopaesOpen can open all loop-AES variations (including multikey) and
it should automatically select proper mode according to number of lines (keys)
in keyfile. So only keysize and hash parameters needed (only if not default,
see cryptsetup --help for default).

Anyway, I promised that there should be some FAQ item about losetup
replacement parameters, So I'll try to prepare something....

Milan



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