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Date: Fri, 17 Aug 2012 04:00:27 +0200
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
CC: Pavel Semjanov <pavel@...janov.com>
Subject: Re: Patch for pkzip_fmt_plug.c from jumbo-6
On 2012-08-17 02:30, magnum wrote:
> On 2012-08-08 23:36, Pavel Semjanov wrote:
>> Any codes for Huffman table check are fairly similar ;)
>
> Maybe on pseudo-code level. I found the pkzip code to be barely usable
> as a starter (or I'm confused).
>
> First, the byte order is different so I had to rework that. Second,
> pkzip first reads nlen, ndist and ncode. I believe RAR has neither.
> Third, pkzip seem to use fixed-length of three bits while RAR use
> bitlength, zerocount of 4 bits each, 20 entries.
>
> I'm not sure I'm even on the right track here.
Never mind, I got it working now. After adjusting for the above, the
below check works fine.
> This code from pkzip:
>
> left = 1;
> for (i = 1; i <= 7; ++i) {
> left <<= 1;
> left -= count[i];
> if (left < 0)
> return 0; /* over-subscribed */
> }
> if (left > 0)
> return 0; /* incomplete set */
>
> ...is this the actual table check? If I replace 7 with 15, should I be
> able to use this provided I built the table correctly?
Lots of thanks for the hints!
magnum
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