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Simple Keygen-Me

 
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DoomsDay
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PostPosted: Tue May 20, 2008 2:27 pm    Post subject: Simple Keygen-Me Reply with quote
I hope you'll have fun solving it out, I had some fun writing it Wink .
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Labyrnth
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PostPosted: Tue May 20, 2008 3:31 pm    Post subject: Reply with quote
CPUID <--- ? Confused
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lurc
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PostPosted: Tue May 20, 2008 3:40 pm    Post subject: Reply with quote
@Labyrnth:
http://en.wikipedia.org/wiki/CPUID

Code:
.text:00401000 ; =============== S U B R O U T I N E =======================================
.text:00401000
.text:00401000 ; Attributes: bp-based frame
.text:00401000
.text:00401000 ; int __stdcall sub_401000(LPCSTR lpString, int)
.text:00401000 sub_401000      proc near               ; CODE XREF: DialogFunc+6Ep
.text:00401000
.text:00401000 var_4           = dword ptr -4
.text:00401000 lpString        = dword ptr  8
.text:00401000 arg_4           = dword ptr  0Ch
.text:00401000
.text:00401000                 push    ebp
.text:00401001                 mov     ebp, esp
.text:00401003                 mov     eax, 1
.text:00401008                 cpuid
.text:0040100A                 push    ecx
.text:0040100B                 push    [ebp+lpString]  ; lpString
.text:0040100E                 call    lstrlenA
.text:00401013                 mov     ecx, eax
.text:00401015                 sub     ecx, 100h
.text:0040101B                 neg     ecx
.text:0040101D                 mov     edi, [ebp+lpString]
.text:00401020
.text:00401020 loc_401020:                             ; CODE XREF: sub_401000+33j
.text:00401020                 ror     word ptr [esp+4+var_4], 5
.text:00401025                 ror     [esp+4+var_4], 0Dh
.text:00401029                 neg     [esp+4+var_4]
.text:0040102C                 mov     al, byte ptr [esp+4+var_4]
.text:0040102F                 or      [ecx+edi-1], al
.text:00401033                 loop    loc_401020
.text:00401035                 add     esp, 4
.text:00401038                 mov     eax, edi
.text:0040103A                 mov     eax, [eax]
.text:0040103C                 sub     eax, [ebp+arg_4]
.text:0040103F                 lea     ebx, unk_403027
.text:00401045                 xlat
.text:00401046                 shl     eax, 18h
.text:00401049                 rol     eax, 8
.text:0040104C                 add     eax, offset aWorngTryAgain ; "Worng, Try again!"
.text:00401051                 pop     ebp
.text:00401052                 retn    8
.text:00401052 sub_401000      endp


This looks like the Encryption or however ur generating the serial, ill look more into it after.
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Labyrnth
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PostPosted: Tue May 20, 2008 4:29 pm    Post subject: Reply with quote
I know what it is mate,

But for a genme?
Why would you use the stepping, model, and family information.
Im getting the idea this genme is machine specific in what results are the real ones.
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DoomsDay
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PostPosted: Tue May 20, 2008 10:28 pm    Post subject: Reply with quote
Labyrnth wrote:
I know what it is mate,

But for a genme?
Why would you use the stepping, model, and family information.
Im getting the idea this genme is machine specific in what results are the real ones.
I used it to generate a different number per machine, because I want you to focus on the algorithm instead of just showing me one possible answer and marking it as solved Smile

Last edited by DoomsDay on Wed May 21, 2008 1:50 am; edited 1 time in total
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Labyrnth
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PostPosted: Wed May 21, 2008 12:22 am    Post subject: Reply with quote
Kinda defeats the purpose of a genme dont yah think?
Since the gen will only be good on a specific machine.

It can still be reversed to work on any machine without genning it tho Razz
I have never attempted to code an actual keygen.
But maybe one day it will give it a shot lol.
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DoomsDay
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PostPosted: Wed May 21, 2008 1:55 am    Post subject: Reply with quote
I believe any non-zero number would be okay in this implementation. Anyways, I think you should crack it first, or step through it, as it's not a regular compare.
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Symbol
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PostPosted: Wed May 21, 2008 2:44 am    Post subject: Reply with quote
At 401045, EBX+AL should point to the value 0x12, the question is what writes to EBX+AL, that I'm still trying to figure out. Surprised

Edit: well it can't point to one of the name/serial addresses, EBX+FF points to 403136 and the name/serial starts at 403137...

Is this even possible?
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Labyrnth
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PostPosted: Wed May 21, 2008 12:06 pm    Post subject: Reply with quote
DoomsDay wrote:
I believe any non-zero number would be okay in this implementation. Anyways, I think you should crack it first, or step through it, as it's not a regular compare.


I have already seen that lol.
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DoomsDay
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PostPosted: Sat May 24, 2008 7:52 am    Post subject: Reply with quote
Well, since no one is willing to actually take a look at it, here's the algorithm:
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Danielb
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PostPosted: Sat May 24, 2008 7:08 pm    Post subject: Reply with quote
---------------------------
Unique ID required
---------------------------
Unique ID required
---------------------------
OK
---------------------------


004010A1 /75 4E JNZ SHORT 004010F1

Password: Danielz Cracked...
11111111111111111111
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atom0s
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PostPosted: Sun May 25, 2008 2:49 am    Post subject: Reply with quote
Danielb wrote:
---------------------------
Unique ID required
---------------------------
Unique ID required
---------------------------
OK
---------------------------


004010A1 /75 4E JNZ SHORT 004010F1

Password: Danielz Cracked...
11111111111111111111


This is a keygen me, not a crackme/patchme. You patched it to take any input which is not the point of the challenge.
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