[dm-crypt] Switch to XTS mode for LUKS in cryptsetup in 1.6.0 (Was Re: [ANNOUNCE] cryptsetup 1.6.0-rc1)

Arno Wagner arno at wagner.name
Sat Jan 5 20:47:14 CET 2013


On Sat, Jan 05, 2013 at 07:25:52PM +0100, Milan Broz wrote:
> On 01/05/2013 06:20 PM, Arno Wagner wrote:
> 
> > What does RHEL use and recommend? Do they always use
> > AES256-XTS or is AES128-XTS offered as an option (not when
> > douing this manually via commandline). I think there would
> > be some benefit to have the same defauls in distro-independent
> > cryptsetup.
> 
> - Encrypted disk installation is using AES-XTS with 512bit key.
> (installer overwrites default. But I know there was no
> real discussion about AES18/256 before this was changed.)

Always nice to know what happens begind the curtains ;-)

> Installed (anaconda) doesn't allow default cipher/key size change
> but allows to "reuse" existing LUKS device.
> 
> - compiled-in cryptsetup default is the same as upstream (CBC with ESSIV)
> (RHEL7 will use XTS as default, I would like to see the same
> default as upstream.)
> (This was mainly for compatibility reasons but now even RHEL5 can
> map XTS LUKS discs.)
> 
> - RHEL in FIPS mode (dmcrypt/LUKS module is still not validated though)
> allows CBC (only with ESSIV) and XTS with AES128/192/256
> 
> Well, I can get more info from independent people here internally.
> 
> My current opinion is to use aes-xts-plain64 with 256bit key
> (IOW use AES128) as independent default for LUKS.

I think that is probably the best option at the moment.

Arno 
-- 
Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno at wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
----
One of the painful things about our time is that those who feel certainty
are stupid, and those with any imagination and understanding are filled
with doubt and indecision. -- Bertrand Russell


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