Introduction

This is gonna be a series of walkthroughs for the OverTheWire Wargame Krypton. This wargame deals with cryptography. We will mainly be looking at some easy encodings and ciphers. It can be played as a beginner and either public tools can be used, or you can program your own.

(If you are new to OverThewWire Wargames and Linux, check out Bandit Walkthrough)

Login

SSH: not needed

Task

Welcome to Krypton! The first level is easy. The following string encodes the password using Base64:

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S1JZUFRPTklTR1JFQVQ=

A little bit of Theory

Base64 is a binary-to-text encoding scheme. Very often recognizable by ‘=’ signs at the end. Six bits are encoded into one of 63 different characters, with the equal sign being used for padding (Base64 Table). There are different tools that allow you to easily encode and decode Base64, such as Online Tool, CyberChef or the command base64.

Solution

I chose the command-line option to decode the password. The command base64 can encode and decode base64. It either takes a file or encodes/decodes the standard input. I used this command to decode the string.

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$ echo S1JZUFRPTklTR1JFQVQ= | base64 -d
XXXXXXXXXXXXXX

https://overthewire.org/wargames/krypton/krypton0.html