downloadbrowseXzzX's XzzX#CrackMe2

Download XzzX-CrackMe2.zip, 3 kb (password: crackmes.de)
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************** XzzX#CrackMe2 **************
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author : XzzX
created : 02/06/2007
language : Assembler / MASM

difficulty: 4/10
goal : write a keygen (has to work with patched and unpatched CrackMe)
patch the advertisement (find a short solution) ;-)
don't patch anything else :-D

info : no fake code
straight algo
fpu knowledge could be usefull ;-)

I know I could have made it harder but my goal was to make an interesting CrackMe not an impossible one.

If you encounter a problem/bug/question/etc feel free to write a comment or send me a pm.

Please send me your solution when you've solved it. ;-) (email in profile)

It is harder than my first one!

gl&hf
XzzX

Difficulty: 4 - Needs special knowledge
Platform: Windows
Language: Assembler

Published: 05. Jun, 2007
Downloads: 485

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Solutions

Solution by red477, published 07. jun, 2007; download (11 kb), password: crackmes.de or browse.

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Discussion and comments

red477
06. Jun 2007		Nice crackme;) I found a name/serial combination...will try to write a keygen soon..
XzzX
Author
06. Jun 2007		I don't like you. You're too fast. ;-)
Send me your keygen as soon as you have one.
Have you already patched the ad?
Dis@sm
11. Jun 2007		We have so different FPUs??
For name="Disasm90"
It must be
0xd4581896 in [0x004046c5] before decryption stage 3
before command
FISTP [0x004046c5]
i have 0xd4581896 in decimal in the top of my FPU
but after it..
[0x004046c5]=0x80000000

any other FISTP command works correcttly
red477
11. Jun 2007		0xd4581896 is a negative number, it is -732424042 in decimal, but not 3562543254. try it;)
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From Intel's Instruction Set Reference:
The FIST instruction converts the value in the ST(0) register to a __signed__ integer and stores the
result in the destination operand.
XzzX
Author
11. Jun 2007		I struggled at exactly the same problem when I tested my crackme and tried to find a key for myself. ;-) But I thought that this is a nice trap so I didn't remove it. :-D

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