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Startet to write something that may make sense.

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takes class-files as input and produces something similar to the JODE (Java Obfuscator/DEcompiler)
original java-File. Of course this can't be perfect: There is no way
to produce the comments or the names of local variables (except when This is a decompiler and optimizer for java I have written in my spare
compiled with <code>-g</code>) and there are often more ways to write time. It takes class files as input and produces something similar to
the same thing. But it does its job quite well.</P> the original java file. Of course this can't be perfect: There is no
way to produce the comments or the names of local variables (except
<h2>Quick Test</h2> when the java files were compiled with `-g') and there are often more
I have now an applet interface to the decompiler. ways to write the same thing. But jode does its job quite well.
<a href="jode-applet.html">Check it out</a>.
Please note that most software licenses forbid to decompile class
<h2>How to get it</h2> files. Use this decompiler only, if you have legal rights to
<P>You can donwload the files in zip form. decompile the class (e.g. on your own code).
The <a href="jode_src.zip">sources</a> contain only the
<code>java</code> files, the <a href="jode_cls.zip">classes</a> The features of the decompilers are:
contain only the <code>class</code> files. </p>
* Systematic flow analysis, that can decompile almost every java code
<p>I also have a <a href="jode.tar.gz">tar.gz file</a> containing only without the need of goto (which doesn't exists in java).
the <code>RCS</code> directories. This is the form I maintain the * Type deduction, that can guess the type of local variables, even if
project, but you probably need unix and a few tools to use them.</p> it is an interface type that doesn't occur in the bytecode.
* Handling of inner and anonymous classes.
<p>There are also some <a href="snapshot/">snapshots</a> that have new * Different indentation styles available.
features like inner and anonymous classes. </p> * It can decompile itself (194 classes) without a single error.
* It can decrypt strings on the fly, that were encrypted by an obfuscator.
<p><a href=".">Click here</a> to browse the files online.
</p> Known bugs of the decompiler:
- If not all dependent classes can be found, the verifier (which is
run before decompilation starts) may exit with a type error. You
<h2>How to use it</h2> can decompile it with --verify=off, but take the warning serious,
that the types may be incorrect. There's sometimes no way to guess
<p>I have some simple step by step pages. There are three the right type, if you don't have access the full class hierarchie.
possibilities:
<ul> But if you don't have the dependent classes, you can't compile the
<li> <a href="jode-useapplet.html"> Using the applet version</a>. code again, anyway.
This can make problem due to java's security policy, but is the
simplest way and works on most platforms. - There may be situations, where the code doesn't understand complex
</li> expressions. In this many ugly temporary variables are used, but the
<li> If you use Windows, you should look on <a code should still be compileable. This does especially happen when
href="jode-win.html">this page</a>.</li> you compile with `-O' flag and javac has inlined some methods.
<li> Unix users should look on <a href="jode-unix.html">this page</a>.
</ul> - Sometimes this program may exit with an Exception or
produce incorrect code. If it produced incorrect code the
<h2>Known bugs</h2> code probably can't be compiled, so that the error can be easily spotted.
If you have one of these problems (they are very rare now), I would
<p>There may be situations, where the code doesn't understand complex be very interested in a bug report (including the .class file, if
expressions. In this many ugly temporary variables are used, but the possible).</p>
code should still be compileable. This does especially happen when
you compile with `-O' flag and javac has inlined some methods. </p> - Sometimes it generates some GOTO expression and labels. This
shouldn't happen any more with javac or jikes. But some flow
<p>Sometimes this program may exit with an <code>Exception</code> or obfuscator likes Zelix Klassmaster may provoke this. In
produce incorrect code. Most time the code can't be compiled, so that that case you can run the Obfuscator first.
it can be easily spotted. If you have one of these problems (except
those that occur on some of the <code>jode.test</code> files, I would
be very interested in a bug report (including the <code>class</code>
file, if possible).</p>
<p>Sometimes it generates some <code>GOTO</code> expression and
labels. This can't be compiled, but shouldn't happen any more with
javac or jikes.</p>
<p>It doesn't handle inner and anonymous classes, yet. You can
decompile them separately, though (use `<code>+$</code>' switch under
jikes), but there is a bug in javac, so that a final variable is twice
initialized. If you encounter this problem just remove the doubled
line by hand. </p>
<p><b>New!</b> The latest <a href="snapshot">snapshot</a> can handle
inner and anonymous classes.</p>
<h2>Why did I wrote it?</h2>
<p>Someday I found <code>guavad</code>, a disassembler for java byte
code (it does similar things like <code>javap&nbsp;-c</code>). I used
it on a class file, and found that it was possible to reconstruct the
original java code. First I did it by hand on some small routines,
but I soon realized that it was a rather stupid task, and that I could
write a <a href="../perl/dasm_to_java.perl"><code>perl</code> script</a>
that does the same. At the end of the next day I had a working
decompiler.</p>
<p>Now while it was working, it was not easy to use. You had to
decompile the code first with a disassembler, cut the method, you
wanted to decompile and then run the perl script on it. So I decided
to get some information of the class files and do this all
automatically. I decided to write it in <code>java</code> now,
because it suited best.</p>
<p>Just for the records: the java code is now more than 50 times The features of the obfuscator are:
bigger than the original perl script and is still growing.</p> * Modular design, you can swap whole classes via the script file.
* Strong analysis, that optimizes fields, expressions that are known
to be constant (and reverts the flow obfuscation of Zelix Klassmaster)
* Can also be used as Optimizer, without any obfuscation at all, it
will preserve the local variable table and line number table.
* Many different renaming options, you can also simply add your own.
<h2>License</h2>
<p>This code is under GNU GPL. That basically means, that you can copy PRELIMINARIES:
or modify this code, as long as you put all your modification under
the GPL again. <A HREF="http://www.gnu.org/copyleft/gpl.html"> Look
here for the complete license</a>.</p>
<hr> You need java jdk1.2 or above, and the gnu getopt package.
<p><A HREF="mailto:Jochen.Hoenicke@Informatik.Uni-Oldenburg.DE"> You should also have the jode-x.x.xx.jar file. Read INSTALL how to
http://www.informatik.uni-oldenburg.de/~delwi/jode/jode.html</A>, last compile it yourself.
updated on <em>17-Jun-1999</em>.</p>
</body> Jode also works with jdk1.1, you need the sun collection classes and
</html> swing in that case and you have to compile the jar-file yourself
USAGE:
First set the classpath. It should contain the jar file
jode-x.x.xx.jar, the gnu getopt package and the sun collection package
for 1.1. For the swingui program you also need swing in you classpath.
You can then decompile a class file with:
java jode.Decompiler --classpath jarfile1.jar,jarfile2.jar org.package.Class
For a graphical user interface based on swing try:
java jode.swingui.Main --classpath jarfile1.jar
The obfuscator/deobfuscator can be run with:
java jode.obfuscator.Main --script obfuscation.script
See XXXX for more information about the script syntax.
HISTORY:
Someday I found guavad, a disassembler for java byte code (it does
similar things like `javap -c'). I used it on a class file, and found
that it was possible to reconstruct the original java code. First I
did it by hand on some small routines, but I soon realized that it was
a rather stupid task, and that I could write a perl script, that does
the same. At the end of the next day I had the first working
decompiler.
Now while it was working, it was not easy to use. You had to
decompile the code first with a disassembler, cut the method, you
wanted to decompile and then run the perl script on it. So I decided
to get some information of the class files and do this all
automatically. I decided to write it in java now, because it suited
best.

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