__imp__'s Keygenme #2
| Download keygenme2.zip, 6 kb (password: crackmes.de) Browse contents of keygenme2.zip This crackme is written in C#, therefore it's for those who familiar with .NET environment (.NET framework v1.0).
Difficulty: 4 - Needs special knowledge | RatingWaiting for at least 3 votes View profile of __imp__ » |
Solutions
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Discussion and comments
| nhc1987 28. Sep 2007 | Rules: ---------------------- It's up to you what tools and methods to use, everything is allowed. ~~~> Patch is ok ? |
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| __imp__ Author 28. Sep 2007 | In order to solve it you have to do the following: 1) Find the appropriate format for name and key. 2) Make a key generator. If you can do this by patching, then it's OK. P.S. Patching the condition code won't do, because it doesn't give a correct key. |
| nhc1987 28. Sep 2007 | Yeah! I found 2 ways to solve this keygen me: 1. Brute force 2. Patch P/s: I patch at "return (num3 == n3)" to "return (num3 != n3)". Is it ok ? |
| zairon Moderator 28. Sep 2007 | > 2) Make a key generator It's obvious, patch is not allowed... |
| nhc1987 28. Sep 2007 | Sorry, If patching is not allowed, I will try another way. |
| rongchaua 28. Sep 2007 | @imp : Can you make a keygen for this keygen me? As I analyse, we must solve an 16 variables-equation system to get the value of array buffer and this value must be integer. I don't think it is imposible to do that. Regards. rca. |
| rongchaua 28. Sep 2007 | "I don't think it is imposible to do that" <-- Sorry, fasle. I want to say I don't think it is possible to do that. |
| __imp__ Author 28. Sep 2007 | It IS possible. You can do this by row reduction of the equation system over a quotient ring. I know, maybe it sounds abstruse, but it wouldn't be very difficult. |
| MR.HAANDI 29. Sep 2007 | @__imp__: did you think of linear dependencies? |
| __imp__ Author 01. Oct 2007 | Of course, I thought about it. Linear dependencies are probable as well as inconsistency. It's well easy to fix it, but I intentionally didn't do that, just not to complicate the algorithm (maybe it was a mistake). |
| MR.HAANDI 01. Oct 2007 | So in the particular case here not every name has a valid key :( *since I made a keygen, which won't work for any name, this is kind of unaesthetic* |
| __imp__ Author 01. Oct 2007 | I think that finding a name that has no valid key is a good problem too. Anyway, if I would have checked that the solution exists and altered the input to fix it, I should have solved the system or calculated a det modulo p myself. In this case, one could just exploit my own code for solution, and I didn't want this. P.S. One possible, but still unaesthetic, solution is to switch letter case in a *bad name* or append '_' to it. |
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