Apktool-2: A Powerful Tool for Reverse Engineering Android Apps
If you are an Android developer, modder, or enthusiast, you might have heard of Apktool, a popular tool for decompiling and recompiling Android APK files. Apktool allows you to access the source code and resources of any Android app, modify them, and rebuild them into a new APK file. This can be useful for various purposes, such as analyzing the app's functionality, adding new features, removing unwanted components, changing the app's appearance, or fixing bugs.
In this article, we will introduce you to Apktool-2, the latest version of Apktool, which has many improvements and bug fixes over the previous versions. We will also show you how to install and use Apktool-2 to decode and recompile Android apps, as well as some common issues and solutions. Finally, we will compare Apktool-2 with some other tools for reverse engineering Android apps, and highlight their pros and cons.
apktool-2
What is Apktool-2 and why use it?
Apktool-2 is a tool for reverse engineering 3rd party, closed, binary Android apps. It can decode resources to nearly original form and rebuild them after making some modifications. It also makes working with an app easier because of the project-like file structure and automation of some repetitive tasks like building APKs, etc.
Apktool-2 is developed by ibotpeaches, a well-known developer in the XDA community. The tool has reached version 2.4 as of March 2019, with many bug fixes and changes. Some of the notable features and benefits of Apktool-2 are:
It supports both AAPT1 and AAPT2 (Android Asset Packaging Tool), which are used to compile and package Android resources.
It can decode most Android apps into smali, which is an intermediate language for Dalvik bytecode. Smali can then be converted to Java for easier analysis.
It can handle various types of resources, such as XML, images, 9-patch images, layouts, menus, animations, etc.
It can handle different versions of Android SDKs and frameworks.
It can handle obfuscated or encrypted apps.
It has a command-line interface as well as a graphical user interface (GUI) for convenience.
It is open-source and free to use.
Apktool-2 installation and usage
To install Apktool-2 on your computer, you will need the following prerequisites:
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A Java Runtime Environment (JRE) or a Java Development Kit (JDK).
An Android SDK installed on your computer.
The apktool.jar file downloaded from .
The apktool.bat file (for Windows) or the apktool script (for Linux/Mac) downloaded from .
To install Apktool-2, follow these steps:
Copy the apktool.jar file to a folder on your computer (e.g., C:\apktool).
tool.jar file.
Add the folder where you copied the apktool files to your system's PATH variable. This will allow you to run apktool from any directory.
Open a command prompt or a terminal and type apktool to verify that it is installed correctly. You should see a help message with the available options and commands.
To use Apktool-2, you will need an APK file that you want to decode or recompile. You can obtain an APK file from various sources, such as downloading it from the Google Play Store, extracting it from your device using ADB, or finding it online. However, be careful not to violate any intellectual property rights or terms of service when obtaining APK files.
How to decode and recompile Android apps with Apktool-2
Once you have Apktool-2 installed and an APK file ready, you can start decoding and recompiling Android apps with Apktool-2. In this section, we will show you how to do that using both the command line and the GUI interface.
Decoding an APK file
Decoding an APK file means extracting its contents into a folder that contains the source code, resources, manifest, certificates, and other files. This will allow you to view and modify the app's components using your preferred text editor or IDE.
Using the command line
To decode an APK file using the command line, follow these steps:
Navigate to the folder where you have the APK file that you want to decode (e.g., C:\apkfiles).
Type apktool d -o . For example, apktool d myapp.apk -o myapp_decoded. This will create a folder named myapp_decoded in the same directory as the APK file, and extract its contents there.
Wait for the process to finish. You should see a message saying "I: Using Apktool 2.x.x on " and "I: Copying assets and libs..." followed by "I: Copying unknown files..." and "I: Copying original files...". Finally, you should see a message saying "I: Built apk..."
Open the output folder and explore its contents. You should see a folder structure similar to this:
myapp_decoded AndroidManifest.xml apktool.yml assets build lib original res smali
The most important folders are:
AndroidManifest.xml: This is the app's manifest file, which contains information about the app's name, version, permissions, activities, services, etc.
assets: This folder contains any files that are not compiled into resources, such as fonts, sounds, videos, etc.
lib: This folder contains any native libraries that are used by the app, such as .so files.
original: This folder contains the original META-INF folder of the APK file, which contains the app's certificates and signatures.
res: This folder contains all the resources of the app, such as XML files, images, 9-patch images, layouts, menus, animations, etc.
smali: This folder contains all the source code of the app in smali format, which is an intermediate language for Dalvik bytecode. Each smali file corresponds to a Java class in the app.
Using the GUI interface
If you prefer a graphical user interface over the command line, you can use Apktool-2 GUI, which is a wrapper for Apktool-2 that provides a simple and intuitive interface for decoding and recompiling APK files. To use Apktool-2 GUI, follow these steps:
Download Apktool-2 GUI from .
Extract the zip file to a folder on your computer (e.g., C:\apktoolgui).
Run Apktool_2.x.x_GUI.jar by double-clicking on it or using java -jar Apktool_2.x.x_GUI.jar in a command prompt or terminal.
You should see a window like this:
![Apktool-2 GUI]
Select the APK file that you want to decode by clicking on the "Select APK" button and browsing to its location.
Select the output folder where you want to save the decoded files by clicking on the "Select Output" button and browsing to its location.
Click on the "Decode APK" button to start the decoding process. You should see a progress bar and a log window showing the output of Apktool-2.
Wait for the process to finish. You should see a message saying "APK decoded successfully" and a folder icon that opens the output folder when clicked.
Open the output folder and explore its contents. You should see a similar folder structure as described in the previous section.
Recompiling an APK file
Recompiling an APK file means building a new APK file from the decoded files that you have modified. This will allow you to test your changes on your device or emulator, or share your modified app with others.
Making modifications to the decoded files
Before you recompile an APK file, you need to make some modifications to the decoded files according to your needs and preferences. You can use any text editor or IDE that supports XML and smali syntax highlighting and editing, such as Notepad++, Sublime Text, Visual Studio Code, Android Studio, etc.
Some of the common modifications that you can make are:
Changing the app's name, icon, version, package name, permissions, etc. in the AndroidManifest.xml file.
Changing the app's appearance, layout, colors, fonts, images, etc. in the res folder.
Changing the app's functionality, logic, algorithms, variables, methods, classes, etc. in the smali folder.
Adding or removing any files or folders that you want or don't want in the app.
However, be careful not to make any changes that might break the app's functionality or compatibility, such as deleting essential files or folders, changing important values or constants, renaming or deleting classes or methods that are referenced elsewhere, etc. Also, be aware of any legal or ethical implications of modifying an app that is not yours.
Building the APK file
After you have made your modifications to the decoded files, you can build a new APK file from them using Apktool-2. To do that, follow these steps:
Using the command line
Navigate to the folder where you have the decoded files that you want to recompile (e.g., C:\apkfiles\myapp_decoded).
Type apktool b . For example, apktool b myapp_decoded. This will create a new APK file named myapp_decoded.apk in a subfolder named dist inside the output folder.
Wait for the process to finish. You should see a message saying "I: Using Apktool 2.x.x" and "I: Checking whether sources has changed..." followed by "I: Smaling smali folder into classes.dex..." and "I: Building resources...". Finally, you should see a message saying "I: Built apk..."
Open the dist subfolder and find your new APK file. You can rename it if you want.
Using the GUI interface
Run Apktool_2.x.x_GUI.jar by double-clicking on it or using java -jar Apktool_2.x.x_GUI.jar in a command prompt or terminal.
You should see a window like this:
![Apktool-2 GUI]
Select the folder where you have the decoded files that you want to recompile by clicking on the "Select Project" button and browsing to its location.
Select the output folder where you want to save the new APK file by clicking on the "Select Output" button and browsing to its location.
Click on the "Build APK" button to start the recompiling process. You should see a progress bar and a log window showing the output of Apktool-2.
Wait for the process to finish. You should see a message saying "APK built successfully" and a folder icon that opens the output folder when clicked.
Open the output folder and find your new APK file. You can rename it if you want.
Troubleshooting common errors and issues
Sometimes, you might encounter some errors or issues when decoding or recompiling APK files with Apktool-2. Here are some of the common ones and how to fix them:
Error/IssueSolution
"Exception in thread "main" brut.androlib.AndrolibException: Could not decode arsc file"This means that Apktool-2 could not decode the resources.arsc file, which contains information about the app's resources. This could be due to various reasons, such as encryption, obfuscation, or corruption of the file. To fix this, you can try using a different version of Apktool-2, or use another tool like Jadx to decode the APK file.
"Exception in thread "main" brut.androlib.AndrolibException: brut.common.BrutException: could not exec (exit code = 1)"This means that Apktool-2 could not execute a command, such as aapt or zipalign, which are used to compile and package the resources. This could be due to various reasons, such as missing or incompatible dependencies, incorrect PATH variable, or insufficient permissions. To fix this, you can try installing or updating the required dependencies, such as Java, Android SDK, etc., or check your system settings and permissions.
"Installation failed with message Failed to establish session"This means that Apktool-2 could not install the new APK file on your device or emulator. This could be due to various reasons, such as an invalid or mismatched certificate or signature, an incompatible Android version or SDK level, or a corrupted APK file. To fix this, you can try signing the APK file with a valid certificate or signature, using an appropriate Android version or SDK level for your device or emulator, or rebuilding the APK file with Apktool-2.
If you encounter any other errors or issues that are not listed here, you can try searching online for solutions, asking for help on forums like XDA or Stack Overflow, or reporting them on of Apktool-2.
Apktool-2 alternatives and comparisons
Apktool-2 is not the only tool for reverse engineering Android apps. There are many other tools that offer similar or different features and functionalities. In this section, we will introduce some of them and compare them with Apktool-2.
Other tools for reverse engineering Android apps
Here are some of the other tools that you can use for reverse engineering Android apps:
Jadx
Jadx is a tool for decompiling Android apps into Java source code. It can also convert Dalvik bytecode into smali and dot graphs. Jadx has a command-line interface as well as a graphical user interface (GUI) that allows you to browse and search the decompiled code. Jadx is open-source and free to use.
Dex2jar
Dex2jar is a tool for converting Android apps into Java .jar files. It can also convert Dalvik bytecode into smali and Java .class files. Dex2jar has a command-line interface only. Dex2jar is open-source and free to use.
Frida
Frida is a tool for dynamic analysis and manipulation of Android apps. It allows you to inject your own code into the app's process and modify its behavior at runtime. Frida has a command-line interface as well as a Python API that allows you to write scripts and plugins for Frida. Frida is open-source and free to use.
Pros and cons of Apktool-2 vs other tools
Each tool has its own advantages and disadvantages when it comes to reverse engineering Android apps. Here are some of the pros and cons of Apktool-2 compared to the other tools:
ToolProsCons
Apktool-2- Supports both AAPT1 and AAPT2- Can handle various types of resources- Can handle obfuscated or encrypted apps- Has a GUI interface- Cannot decompile smali to Java- Cannot inject code or modify apps at runtime- May encounter errors or issues with some apps
Jadx- Can decompile smali to Java- Can convert Dalvik bytecode to smali and dot graphs- Has a GUI interface that allows browsing and searching the code- Cannot recompile Java to smali or APK- Cannot handle resources or manifest files- May produce inaccurate or incomplete Java code
Dex2jar- Can convert smali to Java .jar files- Can convert Dalvik bytecode to smali and Java .class files- Cannot recompile Java to smali or APK- Cannot handle resources or manifest files- May produce inaccurate or incomplete Java code
Frida- Can inject code or modify apps at runtime- Can write scripts and plugins for Frida using Python API- Cannot decode or recompile APK files- Cannot handle resources or manifest files- Requires root access or a patched Android device
Conclusion and FAQs
In this article, we have introduced you to Apktool-2, a powerful tool for reverse engineering Android apps. We have shown you how to install and use Apktool-2 to decode and recompile APK files, as well as some common errors and solutions. We have also compared Apktool-2 with some other tools for reverse engineering Android apps, and highlighted their pros and cons.
We hope that this article has been helpful and informative for you. If you have any questions or feedback, please feel free to leave a comment below. Here are some frequently asked questions that you might find useful:
FAQs
Q: Is Apktool-2 legal?A: Apktool-2 is legal as long as you use it for educational or personal purposes only, and do not violate any intellectual property rights or terms of service of the app owners or developers. However, different countries may have different laws regarding reverse engineering, so please check your local laws before using Apktool-2.
Q: Is Apktool-2 safe?A: Apktool-2 is safe as long as you download it from , and verify its checksums or signatures. However, be careful not to download any malicious APK files or modify any sensitive files that might harm your device or data.
Q: How can I sign the APK file after recompiling it?A: You can sign the APK file using various tools, such as jarsigner, apksigner, zipalign, etc. You can also use , which is a simple tool for signing APK files with a test certificate.
Q: How can I install the APK file on my device or emulator?A: You can install the APK file using various methods, such as ADB, Android Studio, File Manager, etc. You can also use , which is a simple tool for installing APK files on your device or emulator.
where you can find the documentation, the source code, the changelog, the issues, and the releases of Apktool-2. You can also join of Apktool-2, where you can chat with other users and developers of Apktool-2.
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