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  #1  
Old 07-02-2004, 09:22
Mitchjs
 
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HELP, CRC32

I need someone skills here

if i got a CRC32 of $44AA4E6A

and i next a text string that crc32's to that
using only numbers and letters

how can i work it backwards?

if someone knows how, can they post some text...

thanks!

mitch
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  #2  
Old 07-02-2004, 10:58
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google for "CRC32" + "reversing"
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  #3  
Old 07-02-2004, 11:08
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Hey.....

That's my line.

Regards,
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  #4  
Old 07-02-2004, 12:11
FiNALSErAPH FiNALSErAPH is offline
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AqHI0F20A631-UFO
58RJ87818080-UFO
Ngkr6CC75340-UFO
1V2kE87C7340-UFO
zmQi9CD75500-UFO
dQToB1F78D20-UFO
gKCu6AFDFB00-UFO
.
.
.
all these string CRC32=BB55B195

CRC32 is NOT a one-way HASH like MD5...etc...
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  #5  
Old 07-02-2004, 13:15
Mitchjs
 
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I ofcourse googled!!!

i found the reversing... but was still at losss

I wrote a small vb ap, to randomly generate text strings
and CRC32 them...

figuring id get one soon.

it ran for 20 hours, nadda

FiNALSErAPH, can you make me a string for my crc32?

CRC32 = 44AA4E6A


mitch
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  #6  
Old 07-03-2004, 02:15
gigaman gigaman is offline
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20 hours? Are you sure your algorithm (or the random generator) is correct?

Long time ago, I wrote a bruteforcer for CRC32 (even before I calculated how to compute it directly ) - and on Pentium 3 1.5 GHz is takes slighly over a minute to check the 2^32 possibilities.
It generates binary data (not just "numbers and letters")... but a simple algorithm that tries random texts should be about the same, i.e. getting the result in about half a time (in average).
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  #7  
Old 07-03-2004, 11:33
FiNALSErAPH FiNALSErAPH is offline
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Quote:
Originally Posted by Mitchjs
I ofcourse googled!!!

i found the reversing... but was still at losss

I wrote a small vb ap, to randomly generate text strings
and CRC32 them...

figuring id get one soon.

it ran for 20 hours, nadda

FiNALSErAPH, can you make me a string for my crc32?

CRC32 = 44AA4E6A


mitch
1f1hBEFF6171-UFO
C3NQD2F41542-UFO
44lY10712D92-UFO
MBU120C3A3A3-UFO
5SXM733B9FD0-UFO
85Nr1D408CF0-UFO
syxb454ACB60-UFO
.
.
.
0xBB55B195 ^ 0xFFFFFFFF = 0x44AA4E6A

^_^

read this tut...

Title : CRC and how to Reverse it
Author : Anarchriz/DREAD
Release Date : 29 april 1999 (last modification 30 april 1999)
Difficulty : beginner to advanced
Target : CRC algorithm
Tools : QEdit 2.1 (the best!) & Wordpad & some CRC progs
Description : A CRC Tutorial & The c00l way to Reverse CRC


CRC and how to Reverse it
.
.
.
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  #8  
Old 07-03-2004, 20:44
arz
 
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Knocked this out a while ago, and should do what you want, more or less.
It isn't base16 so you may want to adjust the src and recompile.

arz...
Attached Files
File Type: rar crc32_str_gen.rar (26.1 KB, 35 views)
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  #9  
Old 07-04-2004, 01:20
Mitchjs
 
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Thanks FiNALSErAPH


im not 100% sure what you mean by

0xBB55B195 ^ 0xFFFFFFFF = 0x44AA4E6A

yes that statement above is true

but why did u calculate bb55b195's strings 1 first time?

bear with me... for being blind here...

mitch
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