<h1>angstromCTF 2016 - Java is the Best</h1>Category: Reversing Score: 50<h2>Description</h2>What kind of input makes this program happy?<h2>Solving the challenge</h2><span>I decompiled the .class file with jad
</span>
# jad SuperSecure.class
 Parsing SuperSecure.class...The class file version is 51.0 (only 45.3, 46.0 and 47.0 are supported)


 Generating SuperSecure.jad
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Looking at the decompiled I could read the flag directly

.# cat SuperSecure.jad
// Decompiled by Jad v1.5.8e. Copyright 2001 Pavel Kouznetsov.
// Jad home page: http://www.geocities.com/kpdus/jad.html
// Decompiler options: packimports(3)
// Source File Name: SuperSecure.java

import java.io.PrintStream;

public class SuperSecure
{

public SuperSecure()
{
}

public static void main(String args[])
{
if(args[0].charAt(0) == 'd' && args[0].charAt(1) == 'o' && args[0].charAt(2) == 'n' && args[0].charAt(3) == 't' && args[0].charAt(4) == '_' && args[0].charAt(5) == 'u' && args[0].charAt(6) == 's' && args[0].charAt(7) == 'e' && args[0].charAt(8) == '_' && args[0].charAt(9) == 'j' && args[0].charAt(10) == 'a' && args[0].charAt(11) == 'v' && args[0].charAt(12) == 'a' && args[0].charAt(13) == '_' && args[0].charAt(14) == 'i' && args[0].charAt(15) == 'f' && args[0].charAt(16) == '_' && args[0].charAt(17) == 'y' && args[0].charAt(18) == 'o' && args[0].charAt(19) == 'u' && args[0].charAt(20) == '_' && args[0].charAt(21) == 'w' && args[0].charAt(22) == 'a' && args[0].charAt(23) == 'n' && args[0].charAt(24) == 'n' && args[0].charAt(25) == 'a' && args[0].charAt(26) == '_' && args[0].charAt(27) == 'h' && args[0].charAt(28) == 'i' && args[0].charAt(29) == 'd' && args[0].charAt(30) == 'e' && args[0].charAt(31) == '_' && args[0].charAt(32) == 'c' && args[0].charAt(33) == 'o' && args[0].charAt(34) == 'd' && args[0].charAt(35) == 'e')
System.out.println("Hooray!");
}
}
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Flag: dont_use_java_if_you_wanna_hide_code</span>