[dm-crypt] LUKS & search for passphrase using dictionary

[dm-crypt] LUKS & search for passphrase using dictionary

[Milan Broz]

Hi,

From time to time someone tries to recover (or crack) LUKS passphrase
using dictionary lists.
I saw lately even some crazy patches for cryptsetup doing that.

Please do not patch source or create some slow bash scripts
(initialization and memory locking cost resources).
Just use libcryptsetup. I added some example how to do it, see

http://code.google.com/p/cryptsetup/source/browse/#git%2Fmisc%2Fdict_search

e.g. for JTR known password list you can run (on quadcore cpu here)
  # luks_dict test.img /usr/share/john/password.lst 4

Then read FAQ how LUKS keyslot iterations slow down these attacks...

It is just quickly written example, perhaps with some bugs.

Anyway, enjoy :)
Milan

p.s.
If you really run this, compile cryptsetup with openssl support
(configure --with-crypto_backend=openssl) it is quicker than default gcrypt. 

Re: [dm-crypt] LUKS & search for passphrase using dictionary

[Arno Wagner]

On Fri, Jul 20, 2012 at 12:48:17AM +0200, Milan Broz wrote:
> Hi,
> 
> From time to time someone tries to recover (or crack) LUKS passphrase
> using dictionary lists.
> I saw lately even some crazy patches for cryptsetup doing that.

Urgh :-)

> Please do not patch source or create some slow bash scripts
> (initialization and memory locking cost resources).
> Just use libcryptsetup. I added some example how to do it, see
> 
> http://code.google.com/p/cryptsetup/source/browse/#git%2Fmisc%2Fdict_search


Cool! Nicely compact as any good piece of example code 
should be. I also like the multi-process capability.
 

> e.g. for JTR known password list you can run (on quadcore cpu here)
>   # luks_dict test.img /usr/share/john/password.lst 4
> 
> Then read FAQ how LUKS keyslot iterations slow down these attacks...


Specifically, FAQ items 5.7, 5.8 and 5.9 can give you some
insight about the amount of effort you can expect.


> It is just quickly written example, perhaps with some bugs.
> 
> Anyway, enjoy :)
> Milan
> 
> p.s.
> If you really run this, compile cryptsetup with openssl support
> (configure --with-crypto_backend=openssl) it is quicker than default gcrypt. 
> 
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> 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 
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----
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