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Date: Mon, 27 Jul 2015 11:33:31 +0200
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: Re: auditing our use of FMT_* flags
On 2015-07-27 10:27, Kai Zhao wrote:
> formats.h: 51~60
>
> /*
> * This flag must be set for formats that do UCS-2, UTF-16 or some other
> wide
> * encoding internally (eg. most Microsoft formats). The most common problem
> * with formats not fully Unicode-aware is when a format like this is
> hard-coded
> * to convert from ISO-8859-1 (ie. by just inserting 0x00, effectively just
> * casting every char to a short). Such formats MUST set FMT_UNICODE and
> MUST
> * NOT set FMT_UTF8, or users will get false negatives when using UTF-8 or
> * codepages.
> */
> #define FMT_UNICODE 0x00000004
>
> "Such formats MUST set FMT_UNICODE and MUST NOT set FMT_UTF8"
> Here "Such formats" points to "The most common problem with formats..." ?
>
> Can anyone explain this ? Is there any example ?
>
> I have found that there are only two formats which set FMT_UNICODE and
> NOT set FMT_UTF8. They are:
>
> opencl_mscash_fmt_plug.c, opencl_nt_fmt_plug.c
This means they can currently only convert ISO-8859-1 to UTF-16/UCS-2.
This is how Hashcat and most other crackers do it, because it's simple
and fast code.
> There are 27 formats which both set FMT_UNICODE and SET FMT_UTF8.
This means they can convert any supported encoding to UTF-16/UCS-2. That
involves a lot more code.
The flags ensure we bail with error instead of chugging along with false
negatives:
$ ../run/john -form:nt-opencl test.in -w:rockyou_utf8.lst -enc:utf8
This format does not yet support other encodings than ISO-8859-1
$ ../run/john -form:nt-opencl test.in -w:rockyou_8859_1.lst -enc:8859-1
Loaded 1 password hash (nt-opencl, NT [MD4 OpenCL])
Press 'q' or Ctrl-C to abort, almost any other key for status
0g 0:00:00:00 DONE (2015-07-27 11:29) 0g/s 7708p/s 7708c/s 7708C/s
elles1992..Vk122503
Session completed
magnum
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