downloadbrowseBUBlic's Backtracking #1

Download Backtracking_#1_KeygenMe_by_BUBlic.zip, 32 kb (password: crackmes.de)
Browse contents of Backtracking_#1_KeygenMe_by_BUBlic.zip

Here comes the first keygenme from my new keygenme series, I think this one is nice, if you have to kill a hour.

"Backtracking is a type of algorithm that is a refinement of brute force search. In backtracking, multiple solutions can be eliminated without being explicitly examined, by using specific properties of the problem." (Wikipedia)

Attention: the whole check procedure is about ~40 asm lines, so this one is not for those of you, who want to learn asm, but for those who like clean algorithms and thinking about simple but still interesting problems. So write a keygen ;)

Difficulty: 3 - Getting harder
Platform: Windows
Language: C/C++

Published: 17. Jun, 2007
Downloads: 660

Rating

Votes: 4
Crackme is quite nice.

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Solutions

Solution by hound, published 22. jun, 2007; download (18 kb), password: crackmes.de or browse.

hound has rated this crackme as awesome.

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Discussion and comments

TiGa
19. Jun 2007		Is there more than one possible serial?
BUBlic
Author
19. Jun 2007		There are about 10^6 unique serials to solve that problem ;)
Of course it's simple to find a few serials on a piece of paper, but you really solved it, when your keygen got them all.
TiGa
20. Jun 2007		So the keygen needs to find 10^6 answers every time it is run? or just a random valid one each time?
I'm not talking about bruteforcing the whole thing but testing only the plausible ones.
BUBlic
Author
20. Jun 2007		The keygen should not generate all the serials each time, but just throw out some random ones. The keygen algo should be able to generate as many serials as possible above 256 should be ok as well ;)
hound
21. Jun 2007		I think this one is easier than the Xor_2_Zero. Nearly got a keygen made.....
Fun crackme though!
Crosys
23. Jun 2007		Solved it!, really fun crackme, thanks BUBlic
BUBlic
Author
25. Jun 2007		I think I can tell the problem behind it now: it is the 16-queens problem ;) or n-queens

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