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Message-ID: <CANWtx01vqJaPnc5TVqqpv3edF4NnosNoNp19JLtDzs2Jn8xAsQ@mail.gmail.com>
Date: Sun, 24 May 2015 20:58:04 -0400
From: Rich Rumble <richrumble@...il.com>
To: john-users@...ts.openwall.com
Subject: Re: Recovering truecrypt pass-phrase with known keyfile
On Thu, May 21, 2015 at 4:50 PM, Marek Wrzosek <marek.wrzosek@...il.com> wrote:
> W dniu 21.05.2015 o 21:42, Rich Rumble pisze:
>> On Thu, May 21, 2015 at 2:55 PM, magnum <john.magnum@...hmail.com> wrote:
>>> On 2015-05-21 20:30, Rich Rumble wrote:
>>>>
>>>> On Thu, May 21, 2015 at 1:36 PM, magnum <john.magnum@...hmail.com> wrote:
>>>>>
>>>>> On 2015-05-21 19:27, Dhiru Kholia wrote:
>>>>>>
>>>>>>
>>>>>> On Thu, May 21, 2015 at 5:28 PM, Marek Wrzosek <marek.wrzosek@...il.com>
>>>>>> wrote:
>>>>>>>
>>>>>>>
>>>>>>> Lately I've been reading TrueCrypt User Guide and I'm curious. Is it
>>>>>>> possible to recover pass-phrase of truecrypt volume with known keyfile
>>>>>>> using JtR? If not, are there any plans of adding this to john in the
>>>>>>> future?
>>>>>>
>>>>>>
>>>>>>
>>>>>> Seems to be simple enough,
>>>>>>
>>>>>> https://github.com/bwalex/tc-play/blob/master/crypto.c#L201
>>>>>
>>>>>
>>>>>
>>>>> I see nothing there. Isn't that part of the code using already decrypted
>>>>> keyfile data?
>>>>
>>>> If I recall from TC's doc's it read the first 1024 bytes of the
>>>> keyfile and used that as the second part of the password.
>>>> <quote>
>>>> Any kind of file (for example, .txt, .exe, mp3, .avi) may be used as a
>>>> TrueCrypt keyfile. However,
>>>> we recommend that you prefer compressed files, such as .mp3, .jpg,
>>>> .zip, etc. Note that TrueCrypt
>>>> never modifies the keyfile contents. Therefore, it is possible to use,
>>>> for example, five files in your
>>>> large mp3 collection as TrueCrypt keyfiles (and inspection of the
>>>> files will not reveal that they are
>>>> used as keyfiles).
>>>
>>>
>>> I see. So we'd just add ability to use a keyfile in addition to the cracking
>>> we currently have. I thought a keyfile was something like
>>> passphrase->KDF->key but that was not the case.
>> Yeah a TC "keyfile" was supposed to be a 2nd factor that avoided keylogging.
>> -rich
>>
> Keyfile could be used with empty password and in that case one should
> check that without using john.
> In general, keyfile is transformed somehow using hash function and then
> is applied to the password by XOR-ing it together.
> Algorithm is described in Truecrypt User Guide on pages 141 and 142.
> https://download.truecrypt.ch/documentation/TrueCrypt%20User%20Guide.pdf#page=141&zoom=auto,54,771
I've uploaded a few more samples to the wiki:
http://openwall.info/wiki/john/sample-non-hashes?&#TrueCrypt-Volumes
(TrueCrypt-examples.7z)
I created two "normal" and two volumes with a normal and a hidden
volume in them. I tried to vary the algorithms used in each so that
there were good test cases. I did not try to crack them, they all use
at least one key file, some of them use three keyfiles + password. Let
me know if there are any questions about these latest samples, or if
more are desired. Inside the archive is a README with everything that
was used when creating them, I hope it helps!
-rich
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