This is adapted from ACiD BuRN's great essay entitled "JAVA REVERSE ENGINEERING: How to defeat java !"



-----------------------START OF ADAPTION------

Ok , now enough of this keyfile shits , lets look a crackme coded by Mandkind in java
in the text , there is no html to test the serial or something , but it is not needed heh!
As always, decompile the .class , and open the jad output file with notepad !!
and we can see:

---------------------------------Start of CrackMe.jad-------------------------------------------


   public CrackMe()
    {
    }

    public static void main(String args[])
    {
        if(args.length != 1)
        {
            System.out.println("Usage: java CrackMe Registration Code");
            System.exit(0);
        }
        System.out.println("");
        System.out.println("");
        System.out.println("Welcome to ManKind's Java CrackMe 0.1");
        System.out.println("=====================================");
        System.out.println("This is an Alpha Test of ManKind's Java CrackMe, please do send your comments, suggestions, opinions, feedbacks and support words to me!");
        System.out.println("");
        System.out.println("");
        int i = Integer.valueOf(args[0]).intValue();
        if(i == 0x7f42b)
            System.out.println("Congratulations, you succeeded in cracking this!");
        if(i != 0x7f42b)
            System.out.println("Sorry, invalid registration code. Please try again!");
        System.out.println("");
        System.out.println("");
        System.out.println("This program is Copyright \251 1999 ManKind");
        System.out.println("Service for Mankind");
        System.out.println("mankind001@bigfoot.com");
        System.exit(0);
    }
}


---------------------------------End of CrackMe.jad-------------------------------------------


hehe , it looks nice !
we can see:

"      int i = Integer.valueOf(args[0]).intValue();
        if(i == 0x7f42b)
            System.out.println("Congratulations, you succeeded in cracking this!");
        if(i != 0x7f42b)
            System.out.println("Sorry, invalid registration code. Please try again!");
        System.out.println("");      "




in Visual basic , it looks like this:


IF serial= $7f42b then
msgbox "Congratulations, you succeeded in cracking this!"
Else
msgbox "Sorry, invalid registration code. Please try again!"
End if

the "0x7f42b" is hexadecimal , but we want the good serial , so convert the serial in decimal
with the Windows calculator or using soft ice!
Ctrl+d
? 7b42b

You will see: 521259

------------------END OF ADAPTION--------------------------------

Thanks to ACiD BuRN for this solution. Other people I remember cracking and sending their solutions to me is Nitrus and Latigo(but I deleted their e-mail and even if I don't, I would not prefer to publish their e-mails). Thanks to them too.


ManKind
Service for Mankind
mankind001@bigfoot.com