Reverse engineering part 1: getting the apk file

Reverse engineering, also called back engineering, is the processes of extracting knowledge or design information from anything man-made and re-producing it or re-producing anything based on the extracted information. The process often involves disassembling something (a mechanical device, electronic component, computer program, or biological, chemical, or organic matter) and analyzing its components and workings in detail.

As far as Android is concerned, suppose we have full-working Android app and we would like to find out how a particular layout is structured, how a specific animation is coded, how a visual effect is made. We can do that by reverse-engineering the apk file and extract useful information from it.

There are different tools for doing that and in the following articles we'll have a look at some of the most widely used.

Reverse engineering

Getting the apk file

The first step to reverse-engineer an Android app is getting the apk file, in order to disassemble and analyze it using the different tools available.

From the web

The easiest way to obtain the apk file of a particular app is using one the many online resources available.

For example, using this website:

http://apk-dl.com/

you can paste the Google Play Store Url of the app you're interested in, and the service lets you download the apk file to your pc.

If you download an apk file from the web, like the online service previously mentioned, be aware of the risk of possible viruses or other malware.

From the smartphone

You can also very easily extract the apk file from an app installed on your smartphone.

To do that we can use the adb.exe utility of the Android Sdk platform (you can find it in the folder: Android\sdk\platform-tools).

Just connect the device to your pc and type the following commands in command line...

adb shell pm list packages 

to obtain a list of the apps (packages) installed and find the package you are interested in

adb shell pm path your-package-name

replace "your-package-name" with the name of the desired package

to get the full package name and the name of the app

adb pull full_path_of_the.apk

replace "full_path_of_the.apk" with the full package name of the apk file obtained with the previous command

to get the apk file in the folder where the command is executed