(2009) - Tool to deobfuscate Java codes

Question

Is there a tool to deobfuscate java obfuscated codes?

The codes is extracted from a compiled class but they are obfuscated and non-readable.

Answer 1

Did you try to make the code less obscure with Java Deobfuscator (aka JDO), a kind of smart decompiler?

Currently JDO does the following:

• renames obfuscated methods, variables, constants and class names to be unique and more indicative of their type
• propogates changes throughout the entire source tree (beta)
• has an easy to use GUI
• allow you to specify the name for a field, method and class (new feature!)

Currently JDO does not do the following (but it might one day)

• modify method bytecode in any way

Answer 2

First step would be to learn with which tool it was obfuscated. Maybe there's already a "deobfuscator" around for the particular obfuscator.

On the other hand, you can also just run an IDE and use its refactoring powers. Rename the class, method and variable names to something sensitive. Use your human logical thinking powers to figure what the code actually represents and name them sensitively. And the picture would slowly but surely grow.

Good luck.

Answer 3

Not to gravedig but I wrote a tool that works on most commercial obfuscators

https://github.com/Contra/JMD

Answer 4

I used Java Deobfuscator (aka JDO) but it has a few bugs. It can't work with case sensitive file names. So I've changed the source and uploaded a patch for that in sourceforge. The patch, Download

Answer 5

Most likely only human mindpower to make sense of it. Get the best decompiler available and ponder on its output.

Answer 6

Maybe it will work on Unix/Linux/MacOS?

If so, you could move one step of your process to a VM, in where you unpack the code, before you rename the too long names. How long is the file name limit on Windows?