Date: Sat, 20 Oct 2012 15:23:24 +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 Thu, Oct 18, 2012 at 1:23 PM, Dhiru Kholia <dhiru.kholia@...il.com> wrote: > On Thu, Oct 18, 2012 at 10:34 AM, Solar Designer <solar@...nwall.com> wrote: >> On Thu, Oct 18, 2012 at 10:22:29AM +0530, Dhiru Kholia wrote: >> Huh? GuaPDF cracks these in about the same time that GuaWord/GuaExcel >> do, so I think that you're wrong. Perhaps the MD5s are inside the loop >> only when you're cracking passwords and not keys? > > My bad. You are right. Update: brute-forcing RC4 keyspace for PDF files is a *lot* faster than Office files since it doesn't involve extra MD5 step. I have modified qpdf to do decryption using RC4 key. See https://github.com/kholia/qpdf.git Now all we need are some kind of Rainbow Tables to make cracking faster. -- Cheers, Dhiru
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