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Date: Sat, 20 Oct 2012 10:25:06 +0530
From: Dhiru Kholia <dhiru.kholia@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: cracking 40-bit RC4 keys of Office and PDF files

On Sat, Oct 20, 2012 at 2:23 AM, magnum <john.magnum@...hmail.com> wrote:
> On 18 Oct, 2012, at 6:52 , Dhiru Kholia <dhiru.kholia@...il.com> wrote:
>> On Thu, Oct 18, 2012 at 4:08 AM, magnum <john.magnum@...hmail.com> wrote:
>>> On 14 Oct, 2012, at 10:54 , Dhiru Kholia <dhiru.kholia@...il.com> wrote:
>>>> This program guarantees decryption of office documents which are using RC4 40-bit encryption.
> ...
>>> So what would you do with a cracked key? Is there any free program that can use this RC4 key to unlock a document?
>>
>> Sadly, I couldn't find any program which can do this. I wrote the
>> program for fun. Good luck with the OpenCL implementation.
>
> For a while I thought we could nail this RC4 first, and then do a more standard candidate search aiming for that RC4 key. But it would not help a lot. Perhaps there's code in OpenOffice or LibreOffice that can be ripped for making an "unlocker" but as already discussed, this is not in JtR's scope.

I am working on modifying qpdf program to accept RC4 key for
decrypting pdf files.

After this, I will take a look at patching OpenOffice to do the same
for Office files.

-- 
Cheers,
Dhiru

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