OverTheWire Krypton Wargame Writeup

Table of contents

Intro

It’s been a while since I started learning about cryptography. And I came across OverTheWire community - good-looking hackers.

They have built wargames as fun games to learn security concepts. Today, I will be solving Krypton Wargames.

Krypton (as the name suggests) is all about cryptography and cryptanalysis.

So let’s get started!

Level 0

There are so many ways to solve this level - you can use online tools, write your own python script, or simply write a terminal command (which ever comfortable you feel with). I am going to decode this string using python scirpt.

import base64

decoded_string = base64.b64decode('S1JZUFRPTklTR1JFQVQ=')

print(decoded_string.decode('utf-8'))

KRYPTONISGREAT

At this point we are done with level 0.

Level 01

To solve level 01, we have to login on a remote server using ssh.

ssh [email protected] -p 2231

Password is KRYPTONISGREAT.

Once we are logged in successfully. we will cd to /krypton/ directory and then into /krypton1/.

cd /krypton/krypton1/

Type ls and you’ll see 2 files in the /krypton1/ directory: krypton2 and README.

You can read both files in the terminal by using cat command.

cat README

It tells you about the password which is encrypted in the file krypton2. It also tells about the encryption algorithm used in the file krypton2, ROT13.

cat krypton2

It gives us encrypted password.

Now, let’s decrypt the file krypton2 and get the password.

def rot13(message):
    result = []
    for char in message:
        if 'A' <= char <= 'Z': 
            result.append(chr((ord(char) - ord('A') + 13) % 26 + ord('A')))
        elif 'a' <= char <= 'z': 
            result.append(chr((ord(char) - ord('a') + 13) % 26 + ord('a')))
        else:
            result.append(char)
    return ''.join(result)

message = "YRIRY GJB CNFFJBEQ EBGGRA"
decoded_message = rot13(message)
print(decoded_message)

LEVEL TWO PASSWORD ROTTEN

Here we go. We got the password for level 2.

Level 02