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diff --git a/docs/FAQ.html b/docs/FAQ.html deleted file mode 100644 index 62ebf7b..0000000 --- a/docs/FAQ.html +++ /dev/null @@ -1,285 +0,0 @@ -<!doctype html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> -<html> -<head> -<meta http-equiv="content-type" content="text/html; charset=iso-8859-1"> -<meta http-equiv="content-style-type" content="text/css"> -<link rel="stylesheet" type="text/css" href="style.css"> -<title>ProGuard FAQ</title> -</head> -<body> - -<script type="text/javascript" language="JavaScript"> -<!-- -if (window.self==window.top) - document.write('<a class="largebutton" target="_top" href="index.html#FAQ.html">ProGuard index</a> <a class="largebutton" target="_top" href="http://www.saikoa.com/dexguard">DexGuard</a> <a class="largebutton" target="_top" href="http://www.saikoa.com/">Saikoa</a> <a class="largebutton" target="other" href="http://sourceforge.net/projects/proguard/">Sourceforge</a>') -//--> -</script> -<noscript> -<a class="largebutton" target="_top" href="index.html#FAQ.html">ProGuard index</a> -<a class="largebutton" target="_top" href="http://www.saikoa.com/dexguard">DexGuard</a> -<a class="largebutton" target="_top" href="http://www.saikoa.com/">Saikoa</a> -<a class="largebutton" target="other" href="http://sourceforge.net/projects/proguard/">Sourceforge</a> -</noscript> - -<h2>Frequently Asked Questions</h2> - -<h3>Contents</h3> - -<ol> -<li><a href="#shrinking">What is shrinking?</a></li> -<li><a href="#obfuscation">What is obfuscation?</a></li> -<li><a href="#preverification">What is preverification?</a></li> -<li><a href="#optimization">What kind of optimizations does <b>ProGuard</b> - support?</a></li> -<li><a href="#commercial">Can I use <b>ProGuard</b> to process my commercial - application?</a></li> -<li><a href="#jdk1.4">Does <b>ProGuard</b> work with Java 2, 5, ..., 8?</a></li> -<li><a href="#jme">Does <b>ProGuard</b> work with Java Micro Edition?</a></li> -<li><a href="#android">Does <b>ProGuard</b> work for Google Android - code?</a></li> -<li><a href="#blackberry">Does <b>ProGuard</b> work for Blackberry - code?</a></li> -<li><a href="#ant">Does <b>ProGuard</b> have support for Ant?</a></li> -<li><a href="#gradle">Does <b>ProGuard</b> have support for Gradle?</a></li> -<li><a href="#maven">Does <b>ProGuard</b> have support for Maven?</a></li> -<li><a href="#gui">Does <b>ProGuard</b> come with a GUI?</a></li> -<li><a href="#forname">Does <b>ProGuard</b> handle <code>Class.forName</code> - calls?</a></li> -<li><a href="#resource">Does <b>ProGuard</b> handle resource files?</a></li> -<li><a href="#encrypt">Does <b>ProGuard</b> encrypt string constants?</a></li> -<li><a href="#flow">Does <b>ProGuard</b> perform control flow - obfuscation?</a></li> -<li><a href="#incremental">Does <b>ProGuard</b> support incremental - obfuscation?</a></li> -<li><a href="#keywords">Can <b>ProGuard</b> obfuscate using reserved - keywords?</a></li> -<li><a href="#stacktrace">Can <b>ProGuard</b> reconstruct obfuscated stack - traces?</a></li> -</ol> - -<h3><a name="shrinking">What is shrinking?</a></h3> - -Java source code (.java files) is typically compiled to bytecode (.class -files). Bytecode is more compact than Java source code, but it may still -contain a lot of unused code, especially if it includes program libraries. -Shrinking programs such as <b>ProGuard</b> can analyze bytecode and remove -unused classes, fields, and methods. The program remains functionally -equivalent, including the information given in exception stack traces. - -<h3><a name="obfuscation">What is obfuscation?</a></h3> - -By default, compiled bytecode still contains a lot of debugging information: -source file names, line numbers, field names, method names, argument names, -variable names, etc. This information makes it straightforward to decompile -the bytecode and reverse-engineer entire programs. Sometimes, this is not -desirable. Obfuscators such as <b>ProGuard</b> can remove the debugging -information and replace all names by meaningless character sequences, making -it much harder to reverse-engineer the code. It further compacts the code as a -bonus. The program remains functionally equivalent, except for the class -names, method names, and line numbers given in exception stack traces. - -<h3><a name="preverification">What is preverification?</a></h3> - -When loading class files, the class loader performs some sophisticated -verification of the byte code. This analysis makes sure the code can't -accidentally or intentionally break out of the sandbox of the virtual machine. -Java Micro Edition and Java 6 introduced split verification. This means that -the JME preverifier and the Java 6 compiler add preverification information to -the class files (StackMap and StackMapTable attributes, respectively), in order -to simplify the actual verification step for the class loader. Class files can -then be loaded faster and in a more memory-efficient way. <b>ProGuard</b> can -perform the preverification step too, for instance allowing to retarget older -class files at Java 6. - -<h3><a name="optimization">What kind of optimizations does <b>ProGuard</b> support?</a></h3> - -Apart from removing unused classes, fields, and methods in the shrinking step, -<b>ProGuard</b> can also perform optimizations at the bytecode level, inside -and across methods. Thanks to techniques like control flow analysis, data flow -analysis, partial evaluation, static single assignment, global value numbering, -and liveness analysis, <b>ProGuard</b> can: - -<ul> -<li>Evaluate constant expressions.</li> -<li>Remove unnecessary field accesses and method calls.</li> -<li>Remove unnecessary branches.</li> -<li>Remove unnecessary comparisons and instanceof tests.</li> -<li>Remove unused code blocks.</li> -<li>Merge identical code blocks.</li> -<li>Reduce variable allocation.</li> -<li>Remove write-only fields and unused method parameters.</li> -<li>Inline constant fields, method parameters, and return values.</li> -<li>Inline methods that are short or only called once.</li> -<li>Simplify tail recursion calls.</li> -<li>Merge classes and interfaces.</li> -<li>Make methods private, static, and final when possible.</li> -<li>Make classes static and final when possible.</li> -<li>Replace interfaces that have single implementations.</li> -<li>Perform over 200 peephole optimizations, like replacing ...*2 by - ...<<1.</li> -<li>Optionally remove logging code.</li> -</ul> -The positive effects of these optimizations will depend on your code and on -the virtual machine on which the code is executed. Simple virtual machines may -benefit more than advanced virtual machines with sophisticated JIT compilers. -At the very least, your bytecode may become a bit smaller. -<p> -Some notable optimizations that aren't supported yet: -<ul> -<li>Moving constant expressions out of loops.</li> -<li>Optimizations that require escape analysis - (<a href="http://www.saikoa.com/dexguard" target="_top">DexGuard</a> - does).</li> -</ul> - -<h3><a name="commercial">Can I use <b>ProGuard</b> to process my commercial application?</a></h3> - -Yes, you can. <b>ProGuard</b> itself is distributed under the GPL, but this -doesn't affect the programs that you process. Your code remains yours, and -its license can remain the same. - -<h3><a name="jdk1.4">Does <b>ProGuard</b> work with Java 2, 5, ..., 8?</a></h3> - -Yes, <b>ProGuard</b> supports all JDKs from 1.1 up to and including 8.0. Java -2 introduced some small differences in the class file format. Java 5 added -attributes for generics and for annotations. Java 6 introduced optional -preverification attributes. Java 7 made preverification obligatory and -introduced support for dynamic languages. Java 8 added more attributes and -default methods. <b>ProGuard</b> handles all versions correctly. - -<h3><a name="jme">Does <b>ProGuard</b> work with Java Micro Edition?</a></h3> - -Yes. <b>ProGuard</b> itself runs in Java Standard Edition, but you can freely -specify the run-time environment at which your programs are targeted, -including Java Micro Edition. <b>ProGuard</b> then also performs the required -preverification, producing more compact results than the traditional external -preverifier. -<p> -<b>ProGuard</b> also comes with an obfuscator plug-in for the JME Wireless -Toolkit. - -<h3><a name="android">Does <b>ProGuard</b> work for Google Android code?</a></h3> - -Yes. Google's <code>dx</code> compiler converts ordinary jar files into files -that run on Android devices. By preprocessing the original jar files, -<b>ProGuard</b> can significantly reduce the file sizes and boost the run-time -performance of the code. It is distributed as part of the Android SDK. -<a href="http://www.saikoa.com/dexguard" target="_top"><b>DexGuard</b></a>, -<b>ProGuard</b>'s closed-source sibling for Android, offers additional -optimizations and more application protection. - -<h3><a name="blackberry">Does <b>ProGuard</b> work for Blackberry code?</a></h3> - -It should. RIM's proprietary <code>rapc</code> compiler converts ordinary JME -jar files into cod files that run on Blackberry devices. The compiler performs -quite a few optimizations, but preprocessing the jar files with -<b>ProGuard</b> can generally still reduce the final code size by a few -percent. However, the <code>rapc</code> compiler also seems to contain some -bugs. It sometimes fails on obfuscated code that is valid and accepted by other -JME tools and VMs. Your mileage may therefore vary. - -<h3><a name="ant">Does <b>ProGuard</b> have support for Ant?</a></h3> - -Yes. <b>ProGuard</b> provides an Ant task, so that it integrates seamlessly -into your Ant build process. You can still use configurations in -<b>ProGuard</b>'s own readable format. Alternatively, if you prefer XML, you -can specify the equivalent XML configuration. - -<h3><a name="gradle">Does <b>ProGuard</b> have support for Gradle?</a></h3> - -Yes. <b>ProGuard</b> also provides a Gradle task, so that it integrates into -your Gradle build process. You can specify configurations in -<b>ProGuard</b>'s own format or embedded in the Groovy configuration. - -<h3><a name="maven">Does <b>ProGuard</b> have support for Maven?</a></h3> - -<b>ProGuard</b>'s jar files are also distributed as artefacts from -the <a href="http://search.maven.org/#search|ga|1|g:%22net.sf.proguard%22" -target="other">Maven Central</a> repository. There are some third-party -plugins that support <b>ProGuard</b>, such as the -<a href="http://code.google.com/p/maven-android-plugin/" -target="other">android-maven-plugin</a> and the -<a href="http://mavenproguard.sourceforge.net/" target="other">IDFC Maven -ProGuard Plug-in</a>. -<a href="http://www.saikoa.com/dexguard" target="_top"><b>DexGuard</b></a> -also comes with a Maven plugin. - -<h3><a name="gui">Does <b>ProGuard</b> come with a GUI?</a></h3> - -Yes. First of all, <b>ProGuard</b> is perfectly usable as a command-line tool -that can easily be integrated into any automatic build process. For casual -users, there's also a graphical user interface that simplifies creating, -loading, editing, executing, and saving ProGuard configurations. - -<h3><a name="forname">Does <b>ProGuard</b> handle <code>Class.forName</code> calls?</a></h3> - -Yes. <b>ProGuard</b> automatically handles constructs like -<code>Class.forName("SomeClass")</code> and <code>SomeClass.class</code>. The -referenced classes are preserved in the shrinking phase, and the string -arguments are properly replaced in the obfuscation phase. -<p> -With variable string arguments, it's generally not possible to determine their -possible values. They might be read from a configuration file, for instance. -However, <b>ProGuard</b> will note a number of constructs like -"<code>(SomeClass)Class.forName(variable).newInstance()</code>". These might -be an indication that the class or interface <code>SomeClass</code> and/or its -implementations may need to be preserved. The developer can adapt his -configuration accordingly. - -<h3><a name="resource">Does <b>ProGuard</b> handle resource files?</a></h3> - -Yes. <b>ProGuard</b> copies all non-class resource files, optionally adapting -their names and their contents to the obfuscation that has been applied. - -<h3><a name="encrypt">Does <b>ProGuard</b> encrypt string constants?</a></h3> - -No. String encryption in program code has to be perfectly reversible by -definition, so it only improves the obfuscation level. It increases the -footprint of the code. However, by popular demand, <b>ProGuard</b>'s -closed-source sibling for Android, <a href="http://www.saikoa.com/dexguard" -target="_top"><b>DexGuard</b></a>, does provide string encryption, along with -more protection techniques against static and dynamic analysis. - -<h3><a name="flow">Does <b>ProGuard</b> perform flow obfuscation?</a></h3> - -Not explicitly. Control flow obfuscation injects additional branches into the -bytecode, in an attempt to fool decompilers. <b>ProGuard</b> does not do this, -in order to avoid any negative effects on performance and size. However, the -optimization step often already restructures the code to the point where most -decompilers get confused. - -<h3><a name="incremental">Does <b>ProGuard</b> support incremental obfuscation?</a></h3> - -Yes. This feature allows you to specify a previous obfuscation mapping file in -a new obfuscation step, in order to produce add-ons or patches for obfuscated -code. - -<h3><a name="keywords">Can <b>ProGuard</b> obfuscate using reserved keywords?</a></h3> - -Yes. You can specify your own obfuscation dictionary, such as a list of -reserved key words, identifiers with foreign characters, random source files, -or a text by Shakespeare. Note that this hardly improves the obfuscation. -Decent decompilers can automatically replace reserved keywords, and the effect -can be undone fairly easily, by obfuscating again with simpler names. - -<h3><a name="stacktrace">Can <b>ProGuard</b> reconstruct obfuscated stack traces?</a></h3> - -Yes. <b>ProGuard</b> comes with a companion tool, <b>ReTrace</b>, that can -'de-obfuscate' stack traces produced by obfuscated applications. The -reconstruction is based on the mapping file that <b>ProGuard</b> can write -out. If line numbers have been obfuscated away, a list of alternative method -names is presented for each obfuscated method name that has an ambiguous -reverse mapping. Please refer to the <a href="manual/index.html">ProGuard User -Manual</a> for more details. -<p> -Erik André at Badoo has written a -<a href="https://techblog.badoo.com/blog/2014/10/08/deobfuscating-hprof-memory-dumps/" -target="other">tool to de-obfuscate HPROF memory dumps</a>. - -<hr /> -<address> -Copyright © 2002-2014 -<a target="other" href="http://www.lafortune.eu/">Eric Lafortune</a> @ <a target="top" href="http://www.saikoa.com/">Saikoa</a>. -</address> -</body> -</html> |