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Date: Thu, 21 May 2015 15:42:50 -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 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

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