---
# System prepended metadata

title: 'NetonCTF:  Mobile_encrypted'

---

# NetonCTF:  Mobile_encrypted
Hello, this is the walkthrough for the challenge Mobile_encrypted.
This is an easy challenge from the cryptography branch, so let's start:

## Decompress the file 

Well, first of all we have to see what type of file is this with the command 

`
file mobile_encrypted
`

![](https://i.imgur.com/CBjG0kS.png)


So now, we have to decompress the bzip2 file with

`
bzip2 -d mobile_encrypted
`

![](https://i.imgur.com/DWztSnl.png)


This will generate a new file 

If you do *file Mobile_encrypted.out*, the console will saw you that is an ASCII file, but if we enter the command *"cat mobile_encrypted.out"* we will see something like this: 

![](https://i.imgur.com/my9smHc.png)


Then we can suppose this is a hex-dump file, so we must use *xxd* and catch the result into an auxiliary file.

![](https://i.imgur.com/hkEOor8.png)

Now, let's see the type of the new file:

![](https://i.imgur.com/v8h19Jv.png)

At this point we can't just do *"gzip -d auxiliar"* because gzip wouldn't be able to decompress the file:

![](https://i.imgur.com/zcgA7z5.png)

So we must do:

![](https://i.imgur.com/A1oX1L0.png)

And then, in that copy of the file we can decompress the file and get an ASCII file

So if we do *cat auxiliar* console will saw this:

![](https://i.imgur.com/bqeGvVk.png)

At this point we have to look for the only line that is not repeated with

`cat auxiliar | sort | uniq -u`

![](https://i.imgur.com/UtLvAoh.png)


As you can see the first part of the line is coded with the keyboard of an old phone



![](https://i.imgur.com/scjlU1U.png) 

And the second part its coded in base64
so if we decoded the two parts of the line, we have this:

 **The flag is NETON{Nokia_360}**
