downloadbrowseprofdracula's Cryptok KeygenMe {3}

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Prof. DrAcULA presents, Cryptok KeygenMe {3}

It is the 3rd KeygenMe in the Cryptok-series.
Hope you enjoy this!

You have to:
1. Code a keygen(inline-keygen is not allowed).
2. On entering a valid-serial, Cryptok {3} displays a Goodboy-messagebox, but its text is encrypted.
You must code a decoding-dll that can decrypt this junk-text to original-text.

Solution for this KeygenMe means;
1. Tutorial explaining how it works.
2. No patching, no self-keygenning.
3. A working keygen and a decoding-dll, with source.

Protection Level : For you to rate it

Hints: I think there are more than enough clues in KeygenMe.

See u with next Cryptok Relaese.

Difficulty: 3 - Getting harder
Platform: Windows
Language: Unspecified/other

Published: 04. Feb, 2007
Downloads: 492


Votes: 3
Crackme is quite nice.

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Solution by red477, published 23. feb, 2007; download (36 kb), password: or browse.

red477 has rated this crackme as awesome.

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Discussion and comments

05. Feb 2007
i am foolish enough to get the prize!:D
but, can you pm me a hint on how to keygen it, do i have to brute force the md5?
at last, I like your crackmes, they are nice;)
05. Feb 2007
Hi red477, when I say : "You have to get foolish", it means you have to let yourself befooled by the KeygenMe(KNOWINGLY). Its a hint in itself :)

And for keygenning, you don't have to bruteforce MD5, because there is nothing to bruteforce in it. Look somewhere else.
10. Feb 2007
i've some problem here:
004022DD |. 81F9 70617274 CMP ECX,74726170

how can it be possible? Ecx points to ntdll.someaddress and it's > than 74XXXXXXh while the Crc16 returns only XXXXh value so the sum never could be equal. Really confused!

Some hints?
11. Feb 2007
@dreak, yes, i am killing by the serial checking routine, too. as you said, to generate a name from a serial is SO EASY, but to me it is nearly impossible to do it the other way...

@Ox87k, bro, this time you have to be careful:) there is a little anti at the beginning, i dont think you overlooked that;)
11. Feb 2007
hi dreak, Ox87k and red477, if you see that code is changing itself, then its definitely (little) SMC[self-modifying-code]. But whether to use SMC, it takes this decision on some valid reason. But whether its using SMC or not both are vital for the solution to keygenme.

And dreak, plz use PM's for sharing solving-methods, instead of posting them here. I think sharing solving-ideas here kills the joy of solution a bit :)
11. Feb 2007
yes mates, sorry i didn't see this trick and thank you for your hint! lol
btw, really hard this time!
11. Feb 2007
i wrote a keygen and submitted it. but probably it is not the way you want;) it works, anyway, and i hope it will be accepted:D
24. Feb 2007
Great crackme.

red477: How did you identify the BigNum library and its functions, did you name them manually? nice solution.

thanks guys!
24. Feb 2007

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