downloadbrowsemucki's crackme#4

Download crackme4.zip, 16 kb (password: crackmes.de)
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This is my fourth crackme (keyfileme + bruteforceme server), now written in Java.

- create a valid keyfile
- write a bruter
- get the serial
- and submit a tutorial

hints:
- serial is short, case insesitive
- to enter serial use a telnetclient at standard-port 23 (command: "telnet localhost")


Tested on WinXP but should also work on other os.

Regards,

mucki

Difficulty: 3 - Getting harder
Platform: Multiplatform
Language: Java

Published: 04. Dec, 2006
Downloads: 576

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Solutions

Solution by macabre, published 11. dec, 2006; download (38 kb), password: crackmes.de or browse.

macabre has rated this crackme as quite nice.

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Discussion and comments

macabre
05. Dec 2006		Sorry but This is the first time I've attempted to crack a java app and I'm running on Linux so it is very possible the issue is mine. I seem to be getting an error and it maybe with my AWT library.... any suggestions?

>>>> java server.CM4
Exception in thread "main" java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(libgcj.so.70)
at server.Loader.load(Loader.java:44)
at server.CM4.main(CM4.java:14)
Caused by: java.awt.AWTError: Cannot load AWT toolkit: gnu.java.awt.peer.gtk.GtkToolkit
at java.awt.Toolkit.getDefaultToolkit(libgcj.so.70)
at java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(libgcj.so.70)
at java.awt.Window.<init>(libgcj.so.70)
at java.awt.Frame.<init>(libgcj.so.70)
at java.awt.Frame.<init>(libgcj.so.70)
at javax.swing.SwingUtilities$OwnerFrame.<init>(libgcj.so.70)
at javax.swing.SwingUtilities.getOwnerFrame(libgcj.so.70)
at javax.swing.JOptionPane.<clinit>(libgcj.so.70)
at java.lang.Class.initializeClass(libgcj.so.70)
at server.KeyfileCheck.main(KeyfileCheck.java:33)
at java.lang.reflect.Method.invoke(libgcj.so.70)
...2 more
Caused by: java.lang.NoSuchMethodError: postChoiceItemEvent (Ljava.lang.String;I)V
<<No stacktrace available>>
macabre
05. Dec 2006		What is sad, is that I decrypted the KeyfileCheck and got the algo out of it, just can't test it... sad that I can crack it but not run it... lol

I'm sure it's just the way my awt is installed... oh well :)
mucki
Author
05. Dec 2006		i tested my crackme under debin linux and a had also errors. i am not sure if that's really a multiplatform one.
macabre
08. Dec 2006		Submitted my tutorial. That was a fun one. Seemed fairly easy and a good learning tool. Level 2 might be more appropriate. I had a good time with this one and learned java in the process :)

Thx Mucki!
mucki
Author
08. Dec 2006		i rated this one level 2. i guess zairon never accepted the difficulty i suggested.
zairon
Moderator
09. Dec 2006		Yes, I changed to 3; it's not a problem to change the level but I wanted to see some feedback before.
For every approved crackme I can't decide the *right* level because it's something personal; you know, my level 3 could be your level 1. I often change the level when I have some feedback through comments/tutorials.
LFalch
03. Apr 2013		I just finished this one! Thanks for the crackme it was a lot of fun.

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