JODE

Sun, 08 Nov 2009 20:32:24 GMT

The optimizer transforms class files in various ways with can be controlled by a script file. It supports the following operations:

Renaming class, method, field and local names to shorter, obfuscated, or unique names or according to a given translation table
Removing debugging information
Removing dead code (classes, fields, methods) and constant fields
Optimizing local variable allocation

Download
:Jode is available in the download area in source or binary form. For compiling the source code, you need several other packages, check the links page. You need a unix like environment for compilation. The simplest way to get it, especially for non unix users, is in precompiled form, though. There are two jar archives in the download area:

jode-1.1-JDK1.1.jar is for JDK 1.1. If you want to use the swing interface, you have to download swing separately, all other packages are already included in the archive.
jode-1.1.jar is for JDK 1.2 or better. It should run without any other package.

Feature are:
Command Line Interface
The most powerful way to start JODE's decompiler is the command line interface. Some people don't like long command lines; they should go to the next section.
Start the class jode.decompiler.Main with the options. The following command will give a complete list of the available commands:

java jode.decompiler.Main --help
If you want to decompile a jar package you can do it this way:
java jode.decompiler.Main --dest srcdir program.jar
If you have installed the batch file/script, you can use it like this:
jode --dest srcdir program.jar

Swing Interface
For the swing interface you need java version 1.2 or the separately available swing package . You can invoke it with the following command:
java jode.swingui.Main classes.jar
resp. jode swi classes.jar
The swing interface will show the package hierarchie of all classes in the classpath on the left side. You can now select a class and the decompiled code will appear on the right side. Via the menu, you may change the classpath or switch between package hierarchie tree and class inheritence tree. The swing interface is very useful to browse through class files if you don't have the source code. You can also use it to trace bugs in library code. It is not meant to generate java files and so you won't find a save option there.
Java Interface
If you want to integrate JODE into your own java program, you can use the jode. Decompiler.decomplier class. Note that the LGPL allows dynamic linking as long as you don't change Jode itself. Please tell me if you use JODE in this way.

ProGuard

Sun, 08 Nov 2009 20:26:22 GMT

Feature are:

Creating more compact code, for smaller code archives, faster transfer across networks, faster loading, and smaller memory footprints.
Making programs and libraries harder to reverse-engineer.
Listing dead code, so it can be removed from the source code.
Retargeting and preverifying existing class files for Java 6, to take full advantage of Java 6's faster class loading.

ProGuard is fast. It only takes seconds to process programs and libraries of several megabytes. The results section presents actual figures for a number of applications. ProGuard's main advantage compared to other Java obfuscators is probably its compact template-based configuration. A few intuitive command line options or a simple configuration file are usually sufficient. For instance, the following configuration option preserves all applets in a jar:

    -keep public class * extends java.applet.Applet

ProGuard is a command-line tool with an optional graphical user interface. It also comes with plugins for Ant and for the JME Wireless Toolkit. ProGuard is probably the most popular java shrinker, optimizer, and obfuscator world-wide. It is being used by developers at companies and organizations like Sun, IBM, HP, Siemens, Nokia, Google, and NATO. It is the default tool in many development environments like Sun's Wireless Toolkit, Netbeans, EclipseME, and more.

Benefits are:

ProGuard typically reads the input jars (or wars, ears, zips, or directories). It then shrinks, optimizes, obfuscates, and preverifies them. Optionally, multiple optimization passes can be performed, each typically followed by another shrinking step. ProGuard writes the processed results to one or more output jars (or wars, ears, zips, or directories). The input may contain resource files, whose names and contents can optionally be updated to reflect the obfuscated class names. ProGuard requires the library jars (or wars, ears, zips, or directories) of the input jars to be specified. These are essentially the libraries that you would need for compiling the code. ProGuard uses them to reconstruct the class dependencies that are necessary for proper processing. The library jars themselves always remain unchanged. You should still put them in the class path of your final application.

In order to determine which code has to be preserved and which code can be discarded or obfuscated, you have to specify one or more entry points to your code. These entry points are typically classes with main methods, applets, midlets, etc.

In the shrinking step, ProGuard starts from these seeds and recursively determines which classes and class members are used. All other classes and class members are discarded.
In the optimization step, ProGuard further optimizes the code. Among other optimizations, classes and methods that are not entry points can be made private, static, or final, unused parameters can be removed, and some methods may be inlined.
In the obfuscation step, ProGuard renames classes and class members that are not entry points. In this entire process, keeping the entry points ensures that they can still be accessed by their original names.
The preverification step is the only step that doesn't have to know the entry points.

Efficient Java tools- Code Obfuscators and Protectors

JODE

ProGuard