saitob's Saibot's Crackme #5
| Download Crackme5.zip, 8 kb (password: crackmes.de) Browse contents of Crackme5.zip Hi again folkz! So I made a challenge for you.
Difficulty: 3 - Getting harder | Send a message to saitob » View profile of saitob » |
Solutions
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Discussion and comments
| bundy 21. Mar 2007 | One of those "Impossible to solve without luck" crackmes. It hashes with MD5 the first line of License.dat file. Then the hash is converted to base64 and compared with fixed string. |
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| boonz 21. Mar 2007 | Hmm, it would appear, that MD5 must be brute-forced... |
| saitob Author 21. Mar 2007 | Good luck, Have fun! ;D |
| boonz 30. Mar 2007 | MD5 is a 128-bit hash, so we have 32-digit-Hashes. Each digit can range from 0..f. That should lead us to 16^32 possible hashes. Is this a crackme based on luck or did I miss something? Are we supposed to use Rainbow tables? |
| bundy 30. Mar 2007 | Don't even try to brute-force it. And I really think even Rainbow tables are useless here. Why? I forgot to add before, that the read line is converted to utf16 (unicode) and after that processed with MD5 [example: bundy -> unicode -> 'b',0,'u',0,'n',0,'d',0,'y',0 -> MD5 -> base64 -> compare with fixed string]. There were some "attacks" on MD5 recently, but I don't think any of those could be applied here (as I recall those were only on finding collisions in reasonable time - feel free to correct me). But maybe here, with those 0 chars between all these read chars, some weakness could be found. But I guess this is a task for some cryptoanalyst/cryptographer out there ;) |
| boonz 31. Mar 2007 | Well, the MD5-Hash we are looking for is 2920729e44b4bfa44d07058ec987e2ff I think I'm gonna give the rainbow tables a shot. This will take a while... :) |
| saitob Author 31. Mar 2007 | Emm, yeah, it WILL take time ;D Im sorry this is a boring and hard challenge if you not patch it, but hey, Im only learning, right! ;D |
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