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Date: Sun, 8 Jul 2012 17:36:39 +0300
From: Milen Rangelov <gat3way@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: RAR's SHA-1 speed on GPU
Just ~7k c/s on Tahiti seems too low. Without HE, speeds should be at least
about 15K c/s for 6-char password...
On Sun, Jul 8, 2012 at 5:24 PM, magnum <john.magnum@...hmail.com> wrote:
> On 2012-07-08 12:04, Solar Designer wrote:
> > On Sat, Jul 07, 2012 at 07:47:37AM +0200, magnum wrote:
> >> An 8-character password results in 7,078,320 bytes of data fed to SHA-1,
> >> that is 110,599 blocks of 64 bytes.
>
> A more correct figure is 7,077,888 bytes, 110592 blocks. Then 16 extra
> blocks are ran for IV, so 110608 should be the correct figure. I just
> fixed a slight bug in rar_fmt for that calculation so it's now like this:
> (strlen(plaintext) * 2 + 8 + 3) * 0x40000 / 64 + 16
>
> The *2 is for Unicode, 8 bytes salt, 3 bytes "serial". 16 extra
> sha1final's are made for calculating IV.
>
> >> gws 33152 4404 c/s 414914052 sha1/s 7.527 sec per
> crypt_all()
> >
> > Hmm, but 4404*110599 = 487M, why does the above show only 415M?
> > Is it counting SHA-1s of sometimes more than one block maybe?
>
> Because this is a six-char password: It was 4404*94213, and after my
> bugfix it's 4404*94224. Current figures for Tahiti:
>
> gws 65536 7175 c/s 676057200 sha1/s 9.133 sec per crypt_all()+
>
> If we can get this figure closer to the 2 billion mentioned for mscash2,
> it would be a nice boost :)
>
> magnum
>
>
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