From: Arno Wagner <arno@wagner.name>
To: dm-crypt@saout.de
Subject: Re: [dm-crypt] SHAx and LUKS/cryptsetup
Date: Sun, 9 Mar 2014 21:15:40 +0100 [thread overview]
Message-ID: <20140309201540.GA26572@tansi.org> (raw)
In-Reply-To: <531CC69E.8000300@gmail.com>
On Sun, Mar 09, 2014 at 20:53:02 CET, Milan Broz wrote:
> On 9.3.2014 19:32, Heinz Diehl wrote:
> >On 09.03.2014, Milan Broz wrote:
> >
> >>If you are using kernel backend (not gcrypt one)
> >
> >I do :-)
> >
> >>sha1 is used as test that interface works.
> >
> >Ok, all good! So this is it. Thanks a lot!
>
> Just to clarity it little bit:
>
> Kernel userspace crypto API was (and still is) quite undocumented,
This is one thing I really do not understand. Doing crypto
right is already hard. With bad documentation it gets worse.
Yet the documentation for kernel, OpenSSL, commercial
libraries I have looked at, Java API, etc. is bad. (for Java
so bad that recently 30'000 Apps on Android were insecure).
I really do not get it. Systematic sabotage of the documentation
seems unlikely, even after Snowden, so I can only conclude
many people implementing crypto have a problem writing
documentation.
> and testing SHA1 (which is mandatory
> for LUKS backend support) was the simplest way how
> to verify kernel backend works reliably.
> (In some kernel versions it was impossible to check if just algorithm
> is missing or the whole kernel socket interface is not available.)
>
> It actually does not compute any sha1 hash, it just tries
> to initialize it.
>
> BTW I found some problems with kernel backend so use with care.
Bad documentation and unreliable. Urgh.
> One problem is e.g. backend cannot use longer
> key for HMAC than 20480 bytes (at least on my 32bit VM),
> which can cause problems for larger keyfiles in PBKDF2.
>
> I have workaround for this but will need some time to finish
> it (I do not want to touch internal PBKDF2 without adding test
> vectors and other tests.)
Very sensible. I completely support this approach.
Arno
>
> Milan
> _______________________________________________
> 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
prev parent reply other threads:[~2014-03-09 20:25 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-09 17:42 [dm-crypt] SHAx and LUKS/cryptsetup Heinz Diehl
2014-03-09 18:01 ` Milan Broz
2014-03-09 18:32 ` Heinz Diehl
2014-03-09 19:53 ` Milan Broz
2014-03-09 20:15 ` Arno Wagner [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140309201540.GA26572@tansi.org \
--to=arno@wagner.name \
--cc=dm-crypt@saout.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.