downloadbrowseCrosys's Keygenme 2008 v1.0

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Keygen only solution.
This time its not long =).

Have fun everyone


Difficulty: 4 - Needs special knowledge
Platform: Windows
Language: C/C++

Published: 11. Jul, 2008
Downloads: 517


Votes: 6
Crackme is quite nice.

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Solution by fusss, published 14. jul, 2008; download (61 kb), password: or browse.

fusss has not rated this crackme yet.

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Discussion and comments

11. Jul 2008
Wooooowww.... nice to see you write sometime again!
I guess this one is very harder :)
Will take a look... thanks mate ;)
11. Jul 2008
Hey mate, dont expect too much , its not very hard.. :)
Have a nice time..
11. Jul 2008
That one was mucho fun mate :) Nice to see another good keygenme... I try to write up a tutorial and keygen for it later one ;)
11. Jul 2008
Thank you zart, you finished it?
11. Jul 2008
Did a quick analyses of it - and understand most of it -- was able to get a valid key. Though this took me my whole extended lunch break! Hhahah - much fun... It was a nice break from trying to do that damned SDDecoder -- If I have a chance sometime soon I'll write up a tutorial and finish it fully with a keygen :)
11. Jul 2008
1st serial is designed for beginners and 2nd serial no. is more harder..
11. Jul 2008
Agreed! Experience will help people for the second serial a lot!
11. Jul 2008
Being a damn number theorist helps for the second serial..
11. Jul 2008
Got it. Wanna something more.

ps. If you want - i can write a small solution
11. Jul 2008

c0: 0x100A8731C4A45A47A0906B10
c1: 0xA8E276C5FDF00FA415C2283C
c2: 0x8DA9A1C93977236D (prime)
c3: 0xC4921F47591E845FB382B3C7 (prime)

Serial syntax: "<dw0>-<dw1>-<dw2>"

Let inv = 1/dw2 (mod c2)
Let hash = Big(first 8 bytes of (MD5(dw0)))

I think this is serial acceptance requirement:

dw1 == [[c0^(hash*inv(mod c2)) * c1^(dw1*inv(mod c2))] (mod c3)] (mod c2)

Is this correct? I don't have near the math skill to do this. Is it a particular cryptosystem we can study?

Zart, I don't believe a word you say. Post your serial?
15. Jul 2008
My god, beautiful keygenme Crosys!
Unfortunatelly i miss that one, i was away from home and now it seems to be too late :)

@fusss: Great solution man ;)
the hoax
30. Apr 2009
Solved. I liked the first part best, since the DSA implementation was pretty straight forward.

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