Apktool in Linux (Ubuntu, Kali Linux, Backbox, and many more)
First, download the Linux wrapper script(click the hyperlink and copy the text inside the new page and

save it as apktool

Download apktool-2 the latest version and

rename the downloaded jar file to apktool.jar

Now move both the files apktool and apktool.jar to

/usr/local/bin

To move the files in the specified directory using command

sudo mv apktool apktool.jar /usr/local/bin

Provide the execution permission to both of the files.

cd /usr/local/bin && chmod +x apktool apktool.jar

Open the terminal by pressing

ctrl + alt + t and type apktool

to check if Apktool has installed correctly or not.

First, download the Linux wrapper script click the hyperlink and copy the text inside the new page and

save it as apktool.bat 

Download apktool-2 the latest version and rename the

downloaded jar file to apktool.jar

Now move both the files

apktool.bat and apktool.jar to C://Windows

If you can not access the

C://Windows directory

No worries, simply paste it anywhere in the

C drive by creating a new folder as apktool

and add it to the

Environment Variables System PATH variable

Now

run apktool in cmd

To open cmd,

press windows+r and type cmd and hit enter

or search for cmd in the program search box and

use the cmd as an administrator

Once cmd gets opened type, apktool to use the functions.

Provide the execution permission to both of the files

 chmod 755 * 

Copy the files to the specified directory so that apktool can work properly.

 sudo cp apktool apktool.jar /usr/local/bin 

Check after moving the files if they exist in the same directory you are supposed to move.

 ls /usr/local/bin |grep "apktool" 

Check for execution permision confirmation. If you want to know more about the execution permissions please visit the blog. Work with Permissions in Linux

 ls -l /usr/local/bin |grep "apktool" 

Try to run apktool by typing the command below.

 apktool 

Check for java version it needs to be java8. I've shown in the video and the below commands how to fix java8 issue in Kali Linux. If you want to do it on Ubuntu 2.4 Please visit this link. How to install JAVA 8 on Ubuntu | Java 8 Error

 java -version

In order to install java8 in Kali Linux please follow the command. Java 8 is required to run the apktool.

 echo "deb http://ppa.launchpad.net/webupd8team/java/ubuntu trusty main" >> /etc/apt/sources.list 

 sudo echo "deb http://ppa.launchpad.net/webupd8team/java/ubuntu trusty main" >> /etc/apt/sources.list 

Update the repositories

 sudo apt-get update 

You can run this command to install the Java8 in Kali Linux

 sudo apt-get install oracle-java8-installer 

This is another command to install java8 In kali liux. If in case 1st command dosent work.

 sudo apt-get install oracle-java8 

Install the default jdk version for your OS

 sudo apt install -y default-jdk 

Please runt this command and select option 2 to select the java8.

 update-alternatives --config java 

 select option 2 and hit enter 

Use this command to decompile the Android apk using apktool

 apktool d fb.apk  

This command is used to build the Android apk again to its original form or after some modifications

 apktool b fb.apk 

Path of build apk for every decompiled application will be the dist directory inside the decompiled path.

 cd fb/dist/ 

Use this command to generate the keystore file to sign the apk. You can change the name of file to anything you want file extension should be .keystore. You can also change the alias according to you. In my case alias name is test. Validity is for 1000 days. Enter the strong password to secure your application key.

 keytool -genkey -V -keystore test.keystore -alias test -keyalg RSA -keysize 2048 -validity 1000 

Sign the apk using Jarsigner prebuild software with java8. Enter the password and fill the owner details to authenticate the identity of developer.

 jarsigner -verbose -sigalg SHA1withRSA -digestalg ShA1 -keystore key.keystore fb.apk test 

Install zipalign, it is used to compress the apk files in the most possible way so that it can work perfectly in any android device.

 apt-get install zipalign 

Update and upgrade the system once again.

 apt-get update 

 apt-get upgrade 

Zipalign the older apk fb.apk with a new name to get the compressed form of the file.

 zipalign -v 4 fb.apk fbSigned.apk 

Change the ownership of the file to copy it somewhere else easily.

 sudo chown efxx:efxx * 

Provide the execution permission to the apk.

 chmod 755 * 

Remove the unwanted files. Now your apk is ready to use.

 rm -rf fb.apk test.keystore  

 sudo rm -rf fb.apk test.keystore