news page: grub argon2 support

Signed-off-by: Leah Rowe <leah@libreboot.org>
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Leah Rowe 2023-08-20 13:44:25 +01:00
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argon2.md
hp8470p_and_dell_t1650.md hp8470p_and_dell_t1650.md
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% Encrypted /boot/ on LUKSv2 with argon2i/id now possible in Libreboot GRUB
% Leah Rowe
% 20 August 2023
<img tabindex=1 class="r" src="https://av.libreboot.org/grub/argon2.jpg" /><span class="f"><img src="https://av.libreboot.org/grub/argon2.jpg" /></span>
Introduction
============
The GRUB payload has supported LUKSv2 for a long time, but only with the
old-school PBKDF2 key derivation method; most Linux dm-crypt setups on LUKSv2
use argon2-based key derivation, which GRUB did not support. This mean either:
use LUKSv2 with PBKDF2 (less secure), or LUKSv2 (ditto), in GRUB.
Today, Libreboot now supports argon2 key derivation in its version of GRUB,
which is offered as a coreboot payload within the Libreboot build system, and
in Libreboot releases.
Why does this matter?
---------------------
Libreboot previously documented how to boot distros from encrypted `/boot`,
which is a boon for security because it's harder to compromise a machine that
has encrypted `/boot` (containing the linux kernel) than if it were unencrypted
like on most LUKS setups. In addition to this, you may consider [GRUB
hardening](../docs/linux/grub_hardening.md) steps such as GPG signature checking
of your installed Linux kernel.
These patches import the PHC argon2 implementation into Libreboot's version
of GRUB:
* <https://browse.libreboot.org/lbmk.git/commit/?id=2c0c521e2f15776fd604f8da3bc924dec95e1fd1>
* <https://browse.libreboot.org/lbmk.git/commit/?id=fd6025321c4ae35e69a75b45d21bfbfb4eb2b3a0>
* <https://browse.libreboot.org/lbmk.git/tree/resources/scripts/build/payload/grub?id=fd6025321c4ae35e69a75b45d21bfbfb4eb2b3a0>
Argon2 is the newer key derivation preferred on modern LUKSv2 setups. It is
strongly recommended that you *upgrade* to argon2id, specifically, for your
setup.
How to get it
-------------
This is unavailable in the current Libreboot 20230625 release, but will be
available in the next Libreboot release. For now, you can compile a ROM image
yourself from the Libreboot build system, lbmk, like so:
[How to build Libreboot ROM images from source](../docs/build/)
Further reading
===============
PHC argon2 implementation
-------------------------
This is the reference argon2 implementation, now used by Libreboot,
and the upstream project for that is hosted here:
<https://github.com/P-H-C/phc-winner-argon2>
Article by Matthew Garrett
--------------------------
[PSA: upgrade your LUKS key derivation
function](https://mjg59.dreamwidth.org/66429.html) by Matthew Garret, talks
further about the importance of secure key derivation (specifically argon2id)
on encrypted Linux setups.
Always use encryption!