downloadbrowseRascal999's Rascal999's [windows] crackme challenge! [Cryptography]

Download, 23 kb (password:
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Your challenge is to decrypt the crackme file using anything you want. I have provided the file used to encrypt/decrypt messages.

You can reverse-engineer the program if you want.

Good luck and read the notes in readme.txt

I only expect brute-force to work.


Difficulty: 7 - Very hard
Platform: Windows
Language: Unspecified/other

Published: 11. Jun, 2008
Downloads: 340


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Solution by MR.HAANDI, published 10. jul, 2012; download (64 kb), password: or browse.

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Discussion and comments

13. Jun 2008
For anyone who may have been confused, the encryption routine in the provided program doesn't read a file, it reads whatever you enter on the "Type>" line - then encrypts it with your two keys and saves it to a file.

Might be a little confusing for ESL people since it wasn't listed in ReadMe :)
13. Jun 2008
woops, I'll make sure to fully document my crackmes in future. Thanks zart
07. Jul 2012
After 1049 days trying nearly 10^18 key combinations the computing cluster got the result:

pass1 = 756384985
pass2 = 999345234
Congratulations on cracking my encryption. I bet you brute forced ;P As you may
have determined pass1 was 756384985 and pass2 was 999345234...

Just kidding, simple meet in the middle attack with about 2^32 iterations. Fun as a riddle, but the algorithm is weak using less than 3 passwords.
07. Jul 2012
Wow, you have me at a loss for words ;) how long did it take? With a MITM attack, did you just use one password or..?
08. Jul 2012
With some probable assumptions it takes ~ 184 seconds on my machine to find a password pair.
I have submitted my solution, so the details about the attack are explained there.
10. Jul 2012
The description is simpler if you recognize the LCG is only used as the seed for Mersenne Twister.

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