[dm-crypt] FAQ rework for LUKS2: First pass done

[dm-crypt] FAQ rework for LUKS2: First pass done

[Arno Wagner]

Hi all,

I just finished the firsy pass through the FAQ to adapt it for LUKS2.
In particular I did the following:

- Clearly state LUKS1 or LUKS2 for things that do not apply to both
- Still uses "LUKS" when both LUKS1 or LUKS2 are affected
- Added references for LUKS2 header spec
- Added specific instructions for LUKS2 where needed
- Added a (currently pretty short) LUKS2 section

If some of you find the time to read through it and let me know
about any errors or omissions, I would apprecitate it.

Also, if you have any suggestions for Section 10 (LUKS2 Questions),
or mabybe even a small item to add, I would appreciate that as
well. In particular, the LUKS2 section would benefit from some
mini-HOWTOs, I think.

As usual, the FAQ is found at 
   https://gitlab.com/cryptsetup/cryptsetup/-/wikis/FrequentlyAskedQuestions

I did update the version in the sources as well, but that may take a while
to propagate.

Regards,
Arno


-- 
Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno@wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
----
A good decision is based on knowledge and not on numbers. -- Plato

If it's in the news, don't worry about it.  The very definition of 
"news" is "something that hardly ever happens." -- Bruce Schneier

Re: [dm-crypt] FAQ rework for LUKS2: First pass done

[JT Morée]

New additions to FAQ are great.  Thank you Arno.

These are the questions I asked on this list within the last few months that I have answers for (thank you all).  My other questions are not yet researched/answered.  Most of them I sent in a previous email.  will send again as finished or on request.  Feel free to add if it seems useful. I don't need attribution as you guys did all the work.
-------------------------------------------

Q: what is an unbound keyslot?

A: Quite simply, an 'unbound key' is an independent 'key' stored in a luks2 keyslot that cannot be used to unlock LUKS2 data device.

More specifically, an 'unbound key' or 'unbound luks2 keyslot' contains a secret stored in LUKS2 keyslot that is not currently associated with any data segment (crypt segment) in
LUKS2 'Segments' section.

Q: What is an unbound keyslot used for?

A: What dm-crypt uses it for as of April 2020:

1) LUKS2 reencryption. Future/new volume key is stored in an unbound
keyslot and it becomes a regular LUKS2 keyslot later when it is used to
actually decrypt/encrypt some crypt segment.

2) Similar use case as 1) is used with wrapped key scheme (used
with e.g. paes cipher). The VK stored in keyslot is in fact binary blob
(encrypted again). The KEK for that binary blob may be refreshed (KEK in
this case is not managed by cryptsetup!) and binary blob gets changed.
For the KEK refresh process 'unbound keyslot' is used. First you store
future effective VK in unbound keyslot and later it gets enforced to
become new real VK (bound to current dm-crypt segment).


JT






On Sunday, April 26, 2020, 9:35:08 AM MST, Arno Wagner <arno@wagner.name> wrote: 





Hi all,

I just finished the firsy pass through the FAQ to adapt it for LUKS2.
In particular I did the following:

- Clearly state LUKS1 or LUKS2 for things that do not apply to both
- Still uses "LUKS" when both LUKS1 or LUKS2 are affected
- Added references for LUKS2 header spec
- Added specific instructions for LUKS2 where needed
- Added a (currently pretty short) LUKS2 section

If some of you find the time to read through it and let me know
about any errors or omissions, I would apprecitate it.

Also, if you have any suggestions for Section 10 (LUKS2 Questions),
or mabybe even a small item to add, I would appreciate that as
well. In particular, the LUKS2 section would benefit from some
mini-HOWTOs, I think.

As usual, the FAQ is found at 
  https://gitlab.com/cryptsetup/cryptsetup/-/wikis/FrequentlyAskedQuestions

I did update the version in the sources as well, but that may take a while
to propagate.

Regards,
Arno


-- 
Arno Wagner,    Dr. sc. techn., Dipl. Inform.,    Email: arno@wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
----
A good decision is based on knowledge and not on numbers. -- Plato

If it's in the news, don't worry about it.  The very definition of 
"news" is "something that hardly ever happens." -- Bruce Schneier
_______________________________________________
dm-crypt mailing list
dm-crypt@saout.de
https://www.saout.de/mailman/listinfo/dm-crypt

Re: [dm-crypt] FAQ rework for LUKS2: First pass done

[Arno Wagner]

Hi JT,

thanks, that is definitely helpful.
Streamlined a bit and added as Item 10.9

Regards,
Arno
 


On Mon, Apr 27, 2020 at 16:37:22 CEST, JT Morée wrote:
> New additions to FAQ are great.  Thank you Arno.
> 
> These are the questions I asked on this list within the last few months that I have answers for (thank you all).  My other questions are not yet researched/answered.  Most of them I sent in a previous email.  will send again as finished or on request.  Feel free to add if it seems useful. I don't need attribution as you guys did all the work.
> -------------------------------------------
> 
> Q: what is an unbound keyslot?
> 
> A: Quite simply, an 'unbound key' is an independent 'key' stored in a luks2 keyslot that cannot be used to unlock LUKS2 data device.
> 
> More specifically, an 'unbound key' or 'unbound luks2 keyslot' contains a secret stored in LUKS2 keyslot that is not currently associated with any data segment (crypt segment) in
> LUKS2 'Segments' section.
> 
> Q: What is an unbound keyslot used for?
> 
> A: What dm-crypt uses it for as of April 2020:
> 
> 1) LUKS2 reencryption. Future/new volume key is stored in an unbound
> keyslot and it becomes a regular LUKS2 keyslot later when it is used to
> actually decrypt/encrypt some crypt segment.
> 
> 2) Similar use case as 1) is used with wrapped key scheme (used
> with e.g. paes cipher). The VK stored in keyslot is in fact binary blob
> (encrypted again). The KEK for that binary blob may be refreshed (KEK in
> this case is not managed by cryptsetup!) and binary blob gets changed.
> For the KEK refresh process 'unbound keyslot' is used. First you store
> future effective VK in unbound keyslot and later it gets enforced to
> become new real VK (bound to current dm-crypt segment).
> 
> 
> JT
> 
> 
> 
> 
> 
> 
> On Sunday, April 26, 2020, 9:35:08 AM MST, Arno Wagner <arno@wagner.name> wrote: 
> 
> 
> 
> 
> 
> Hi all,
> 
> I just finished the firsy pass through the FAQ to adapt it for LUKS2.
> In particular I did the following:
> 
> - Clearly state LUKS1 or LUKS2 for things that do not apply to both
> - Still uses "LUKS" when both LUKS1 or LUKS2 are affected
> - Added references for LUKS2 header spec
> - Added specific instructions for LUKS2 where needed
> - Added a (currently pretty short) LUKS2 section
> 
> If some of you find the time to read through it and let me know
> about any errors or omissions, I would apprecitate it.
> 
> Also, if you have any suggestions for Section 10 (LUKS2 Questions),
> or mabybe even a small item to add, I would appreciate that as
> well. In particular, the LUKS2 section would benefit from some
> mini-HOWTOs, I think.
> 
> As usual, the FAQ is found at 
>   https://gitlab.com/cryptsetup/cryptsetup/-/wikis/FrequentlyAskedQuestions
> 
> I did update the version in the sources as well, but that may take a while
> to propagate.
> 
> Regards,
> Arno
> 
> 
> -- 
> Arno Wagner,    Dr. sc. techn., Dipl. Inform.,    Email: arno@wagner.name
> GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
> ----
> A good decision is based on knowledge and not on numbers. -- Plato
> 
> If it's in the news, don't worry about it.  The very definition of 
> "news" is "something that hardly ever happens." -- Bruce Schneier
> _______________________________________________
> dm-crypt mailing list
> dm-crypt@saout.de
> https://www.saout.de/mailman/listinfo/dm-crypt
> _______________________________________________
> dm-crypt mailing list
> dm-crypt@saout.de
> https://www.saout.de/mailman/listinfo/dm-crypt

-- 
Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno@wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
----
A good decision is based on knowledge and not on numbers. -- Plato

If it's in the news, don't worry about it.  The very definition of 
"news" is "something that hardly ever happens." -- Bruce Schneier