decompiling DEX into Java sourcecode

Question

How can one decompile Android DEX (VM bytecode) files into corresponding Java sourcecode?

Answer 1

With Dedexer, you can disassemble the .dex file into dalvik bytecode (.ddx).

Decompiling towards Java isn't possible as far as I know.
You can read about dalvik bytecode here.

Answer 2

This can be done in following five steps:

This gem does these things for you automatically even the installation of required tools

1. convert apk file to zip
2. unzip the file
3. extract classes.dex from it
4. use dex to jar to convert classes.dex into jar file
5. use jadx gui to open the jar file as java source code

Answer 3

Sometimes you get broken code, when using dex2jar/apktool, most notably in loops. To avoid this, use jadx, which decompiles dalvik bytecode into java source code, without creating a .jar/.class file first as dex2jar does (apktool uses dex2jar I think). It is also open-source and in active development. It even has a GUI, for GUI-fanatics. Try it!

Answer 4

Recent Debian have Python package androguard:

Description-en: full Python tool to play with Android files
 Androguard is a full Python tool to play with Android files.
  * DEX, ODEX
  * APK
  * Android's binary xml
  * Android resources
  * Disassemble DEX/ODEX bytecodes
  * Decompiler for DEX/ODEX files

Install corresponding packages:

sudo apt-get install androguard python-networkx

Decompile DEX file:

$ androdd -i classes.dex -o ./dir-for-output

Extract classes.dex from Apk + Decompile:

$ androdd -i app.apk -o ./dir-for-output

Apk file is nothing more that Java archive (JAR), you may extract files from archive via:

$ unzip app.apk -d ./dir-for-output

Answer 5

It's easy

Get these tools:

1. dex2jar to translate dex files to jar files

2. jd-gui to view the java files in the jar

The source code is quite readable as dex2jar makes some optimizations.

Procedure:

And here's the procedure on how to decompile:

Step 1:

Convert classes.dex in test_apk-debug.apk to test_apk-debug_dex2jar.jar

d2j-dex2jar.sh -f -o output_jar.jar apk_to_decompile.apk
d2j-dex2jar.sh -f -o output_jar.jar dex_to_decompile.dex

Note 1: In the Windows machines all the .sh scripts are replaced by .bat scripts

Note 2: On linux/mac don't forget about sh or bash. The full command should be:

sh d2j-dex2jar.sh -f -o output_jar.jar apk_to_decompile.apk 

Note 3: Also, remember to add execute permission to dex2jar-X.X directory e.g. sudo chmod -R +x dex2jar-2.0

dex2jar documentation

Step 2:

Open the jar in JD-GUI

Answer 6

Since Dheeraj Bhaskar's answer is relatively old as many years past.

Here is my latest (2019 year) answer:

Main Logic

from dex to java sourcecode, currently has two kind of solution:

• One Step: directly convert dex to java sourcecode
• Two Step: first convert dex to jar, second convert jar to java sourcecode

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One step solution: dex directly to java sourcecode

Tools

• jadx

Process

1. download jadx-0.9.0.zip, unzip it, in bin folder can see command line jadx or GUI version jadx-gui, double click to run GUI version: jadx-gui

2. open dex file

then can show java source code:

3. File -> save as gradle project

then got java sourcecode:

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Two Step solution

Step1: dex to jar

Tools

• dex2jar

Process

download dex2jar zip, unzip got d2j-dex2jar.sh, then:

• apk to jar: sh d2j-dex2jar.sh -f ~/path/to/apk_to_decompile.apk
• dex to jar: sh d2j-dex2jar.sh -f ~/path/to/dex_to_decompile.dex

example:

➜  v3.4.8 /Users/crifan/dev/dev_tool/android/reverse_engineering/dex-tools/dex-tools-2.1-SNAPSHOT/d2j-dex2jar.sh -f com.huili.readingclub8825612.dex
dex2jar com.huili.readingclub8825612.dex -> ./com.huili.readingclub8825612-dex2jar.jar
➜  v3.4.8 ll
-rw-------  1 crifan  staff   9.5M  3 21 10:00 com.huili.readingclub8825612-dex2jar.jar
-rw-------  1 crifan  staff   8.4M  3 19 14:04 com.huili.readingclub8825612.dex

Step2: jar to java sourcecode

Tools

• jd-gui: most popular, but many code will decompile error
• CRF: popular, minor code will decompile error
• Procyon: popular, no code decompile error
  • GUI tool based on Procyon
    • Luyten:
    • Bytecode Viewer
• others
  • Krakatau
  • Fernflower
  • old one: AndroChef
  • etc.

Process

here demo Procyon convert jar to java source code:

download procyon-decompiler-0.5.34.jar

then using syntax:

java -jar /path/to/procyon-decompiler-0.5.34.jar -jar your_to_decompile.jar -o outputFolderName

example:

java -jar /Users/crifan/dev/dev_tool/android/reverse_engineering/Procyon/procyon-decompiler-0.5.34.jar -jar com.huili.readingclub8825612-dex2jar.jar -o com.huili.readingclub8825612

using editor VSCode to open exported source code, look like this:

Conclusion

Conversion correctness : Jadx > Procyon > CRF > JD-GUI

Recommend use: (One step solution's) Jadx

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for more detailed explanation, please refer my online Chinese ebook: 安卓应用的安全和破解