Level 11: ROT13 Cipher — Gurumanie Singh

Goal

Level Goal

The password for the next level is stored in data.txt, where all lowercase (a-z) and uppercase (A-Z) letters have been rotated by 13 positions (ROT13).

Solution

Step-by-Step Solution

1. Exit Level 10 and SSH into Level 11

After obtaining the Level 11 password from data.txt in Level 10, exit the current session:

exit

Then connect as bandit11 using the password acquired:

ssh bandit11@bandit.labs.overthewire.org -p 2220

2. List the Home Directory

Once logged in as bandit11, run:

ls

You will see data.txt listed.

3. Inspect `data.txt`

To view its contents:

cat data.txt

The file contains text with all letters rotated by 13 positions. The instructions indicate you must apply a ROT13 transformation to this text.

4. Decode Using `tr`

To reverse the ROT13 encoding, use:

cat data.txt | tr ABCDEFGHIJKLKMOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm

The first string (ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz) represents the original alphabet, and the second string (NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm) shifts each letter by 13 positions. The output reveals the password for bandit12.

5. Alternative `tr` Syntax

The same ROT13 transformation can also be done using:

cat data.txt | tr A-Za-z N-ZA-Mn-za-m

This shorter syntax maps each letter to the character 13 positions ahead in the alphabet. It produces the same decoded output.

Summary

Key Commands

exit — return to your local machine from Level 10.
ssh bandit11@bandit.labs.overthewire.org -p 2220 — connect as bandit11.
ls — list files; shows data.txt.
cat data.txt — view ROT13-encoded contents.
cat data.txt | tr ABCDEFGHIJKLKMOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm — apply ROT13 decoding; retrieve the bandit12 password.
cat data.txt | tr A-Za-z N-ZA-Mn-za-m — alternative, shorter ROT13 decoding syntax.

ROT13 Cipher