CromaxX's KeygenMe #2
| Download KeygenMe_#2_by_CromaxX.zip, 65 kb (password: crackmes.de) Browse contents of KeygenMe_#2_by_CromaxX.zip A simple KeygenMe for newbies, with mathematic calculs !! :) (Packed)
Difficulty: 2 - Needs a little brain (or luck) | Send a message to CromaxX » View profile of CromaxX » |
Solutions
Solution by missing in bytes, published 23. aug, 2005; download (3 kb), password: crackmes.de or browse.
missing in bytes has not rated this crackme yet.
Solution by haggar, published 20. aug, 2005; download (84 kb), password: crackmes.de or browse.
haggar has rated this crackme as boring.
Solution by Ox87k, published 20. aug, 2005; download (30 kb), password: crackmes.de or browse.
Ox87k has rated this crackme as nothing special.
Solution by deroko, published 21. aug, 2005; download (30 kb), password: crackmes.de or browse.
deroko has rated this crackme as quite nice.
The submission of solutions is closed.
Discussion and comments
| haggar 19. Aug 2005 | To easy. Maybe something for biger noobs than me ;) |
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| Immortal_One 19. Aug 2005 | A few bugs found: 1. enter 9 chars on serial crash 2. enter name+serial without code good job message other than that to easy :D |
| CromaxX Author 19. Aug 2005 | Sorry ! I'm repairing this bugs ! I'll upload a new version when it will be done ! |
| deroko 19. Aug 2005 | argh... I've already submitted solution =) |
| CromaxX Author 19. Aug 2005 | Erf... sorry... maybe i'm not obligated to send a new version because the bugs are not very important ! Your aim is to create a keygenme, don't forget ! What do you think ? Upload a new version or give up ? |
| deroko 19. Aug 2005 | I don't know I've created and submitted keygen + small solution, so it's all up to you... If you ask me, it is not a big problem, point was to make keygen =) |
| Ox87k 19. Aug 2005 | i solve it :) submit my solution? |
| CromaxX Author 19. Aug 2005 | okay... so submit your solutions & keygens, i won't upload my release ! Sorry for the bugs one more time ! =) |
| Ox87k 19. Aug 2005 | ok, i submit my keygen, source file and txt with solution ;) thanks for this crackme :) |
| haggar 19. Aug 2005 | What the hell, I submited my solution too. |
| Immortal_One 22. Aug 2005 | CromaxX da bugs are not that important to upload a new version |
| microplant[mp] 22. Dec 2005 | ok, this one is a little older, but since i just started with that stuff, i have a question. i havent read the complete solutions so far, just one part of the code generation. and from what i read, i made my code calculation correct. BUT, my code does not match the one generated. for example: if i have username "!" then i would have the following calculation: (0x21 + 0x3B9ACA00) * (0x21 * 0x01) = (0x3B9ACA21) * (0x21) = 0xAEF40E41 = 2935230017 but the generated code is 640262721. what am i missing ? just gimme the last part of the code puzzle pls, as in the solutions as far as i understand you guys have the same calculation as me. thx in advance. |
| Ox87k 23. Dec 2005 | ur code it's right but after this routine there is: 0040139A 837D E4 00 CMP DWORD PTR SS:[EBP-1C],0 <-+ if result<=0x7FFFFFFF <--------+ 0040139E 79 0B JNS SHORT KeygenMe.004013AB <-+ jump down | 004013A0 8D45 E4 LEA EAX,DWORD PTR SS:[EBP-1C] <- else | 004013A3 8100 00CA9A3B ADD DWORD PTR DS:[EAX],3B9ACA00 <- add result, 0x3B9ACA00 | 004013A9 ^EB EF JMP SHORT KeygenMe.0040139A <- and jump up +--------+ so after code=(0x21 + 0x3B9ACA00) * (0x21 * 0x01); u must to add while(code>0x7FFFFFFF) { code+=0x3B9ACA00; } ;) |
| microplant[mp] 23. Dec 2005 | yes, I read that, but when I enter "E-404" as username, then the jump after 0040139A is taken, and nothin is added. Also, the result of IMUL EAX,EDX is the one showing in the code window of the crackme. But if i calculate that manually, I have a different result. Thats the part what I dont understand. The other question is, how do you know the value 0x7FFFFFFF ? CMP DWORD PTR SS:[EBP-1C],0 <= I cant see anything related to that value here. Maybe my questions are stupid, but since I never coded in ASM I have some trouble with translating the code for my understanding. But thank you for your help so far :) |
| microplant[mp] 23. Dec 2005 | hmm...very curious...I just started coding my KeyGen and my KeyGen is calculating the correct Code :P Maybe I calculated wrong, or the Windows Calc isn´t the best helper :) |
| code_inside 24. Dec 2005 | microplant[mp], That 0x7FFFFFFF thing is because of the Conditional Jump after it, JNS :) |
| Ox87k 24. Dec 2005 | yes i used 0x7FFFFFFF because under the cmp istruction there is a jns :) |
| microplant[mp] 24. Dec 2005 | Ah, thx for the hint. I already finished my KeyGen, but I interpreted that 0040139A 837D E4 00 CMP DWORD PTR SS:[EBP-1C],0 as a check if the code (or serial) is a negative value, and if yes, add 0x3B9ACA00 until its possitive value. I tried my KeyGen with several names, and it always work. So I guess, my idea is correct too :D |
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