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Message-ID: <BLU0-SMTP458DFC799525C5BABFA1E6DFDEA0@phx.gbl>
Date: Mon, 2 Jul 2012 21:36:45 +0200
From: Frank Dittrich <frank_dittrich@...mail.com>
To: john-dev@...ts.openwall.com
Subject: Re: I think I got it

On 07/02/2012 07:41 PM, jfoug wrote:
>> From: Frank Dittrich [mailto:frank_dittrich@...mail.com]
>> Format label                    	dynamic
>> Max. password length in bytes   	82
> 
> I will have to check for sure, but DUE to this being generic, I did make it so it would work with longer PW's.   The format itself, should set the max password length IT wants.  Each sub format will or should know how many bytes are valid.  SSE builds vs non-SSE builds do (or can) change this.
> 
> It appears that this format (dyna 2) is busted, as likely are others.  I will correct this.  Dyna2 in SSE (mmx) builds should truncate any password longer than 55 bytes to only be 55 bytes long.
> 
> 
>> Min. keys per crypt             	1
>> Max. keys per crypt             	128
>> Flags
>> Case sensitive                 	yes
>> Supports 8-bit characters      	yes
>> Converts 8859-1 to UTF-16/UCS-2	no
>> Honours --encoding=NAME        	no
>> False positives possible       	no
>> Uses a bitslice implementation 	no
>> The split() method unifies case	no
>> Number of test cases for --test 	24
>> Algorithm name                  	128/128 SSE2 intrinsics 8x4x4
>> Format name                     	dynamic_2: md5(md5($p)) (e107)
>> Benchmark comment
>> Benchmark length                	-1
>> Binary size                     	16
>> Salt size                       	0
>>
> 
> NOTE, in dyna.conf, the task is MUCH harder, since it does not know how JtR was built.

If you define a dynamic format in a config file and use max. password
length 80, the specific mmx or other implementation that will be used
"knows" the supported max. password length.

So, it could compare the value specified in the format definition,
compare it with the value that can be supported,
fprintf(stderr, "Warning: max. password length reduced from %d to %d\n",
...);
and reduce the max. password length as if
--length=N                force a lower max. length
had been used on the command line.

Frank

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