[dm-crypt] Documentation inconsistency -- On-Disk Format

[dm-crypt] Documentation inconsistency -- On-Disk Format

[Robert Nichols]

I just noticed that in the LUKS On-Disk Format Specification document 1.2.1
http://wiki.cryptsetup.googlecode.com/git/LUKS-standard/on-disk-format.pdf
the LUKS key slots are numbered 1-8, whereas all the tools number them 0-7.
That makes communication difficult.

-- 
Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.

Re: [dm-crypt] Documentation inconsistency -- On-Disk Format

[Milan Broz]

On 11/21/2014 03:51 AM, Robert Nichols wrote:
> I just noticed that in the LUKS On-Disk Format Specification document 1.2.1
> http://wiki.cryptsetup.googlecode.com/git/LUKS-standard/on-disk-format.pdf
> the LUKS key slots are numbered 1-8, whereas all the tools number them 0-7.

It is just for "historic" reasons. I can fix it in documentation but old
documentation is still in place (it is installed e.g. as docs in various distros).
It could make the problem even worse.

(And changing tools means breaking user scripts which is even worse.)

It is not the first standard which uses pseudo-code description while real
implementation differs in details.

> That makes communication difficult.

I do not think so. When dealing with users problem always the tool output
is important. The slot offsets depends on key size so you must have always
proper luksDump output for the device.

Milan

Re: [dm-crypt] Documentation inconsistency -- On-Disk Format

[Arno Wagner]

On Fri, Nov 21, 2014 at 08:32:11 CET, Milan Broz wrote:
> On 11/21/2014 03:51 AM, Robert Nichols wrote:
> > I just noticed that in the LUKS On-Disk Format Specification document 1.2.1
> > http://wiki.cryptsetup.googlecode.com/git/LUKS-standard/on-disk-format.pdf
> > the LUKS key slots are numbered 1-8, whereas all the tools number them 0-7.
> 
> It is just for "historic" reasons. I can fix it in documentation but old
> documentation is still in place (it is installed e.g. as docs in various distros).
> It could make the problem even worse.
> 
> (And changing tools means breaking user scripts which is even worse.)
> 
> It is not the first standard which uses pseudo-code description while real
> implementation differs in details.
> 
> > That makes communication difficult.
> 
> I do not think so. When dealing with users problem always the tool output
> is important. The slot offsets depends on key size so you must have always
> proper luksDump output for the device.
> 
> Milan

I would also not change the tools. And FAQ Item 6.12 provides an
alternate reference with numbering 0-7 and all offsets
in hex and dec. I also do not think changing the spec is needed.

Arno

> 
> 
> _______________________________________________
> dm-crypt mailing list
> dm-crypt@saout.de
> http://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

Re: [dm-crypt] Documentation inconsistency -- On-Disk Format

[Arno Wagner]

So far, this has not been a real problem. You can
also refer to FAQ Item 6.12 to get the 0-7 numbering
with offset in hex and decimal.

Arno

On Fri, Nov 21, 2014 at 03:51:32 CET, Robert Nichols wrote:
> I just noticed that in the LUKS On-Disk Format Specification document 1.2.1
> http://wiki.cryptsetup.googlecode.com/git/LUKS-standard/on-disk-format.pdf
> the LUKS key slots are numbered 1-8, whereas all the tools number them 0-7.
> That makes communication difficult.
> 
> -- 
> Bob Nichols     "NOSPAM" is really part of my email address.
>                 Do NOT delete it.
> 
> _______________________________________________
> dm-crypt mailing list
> dm-crypt@saout.de
> http://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