OverTheWire’s Krypton is a beginner-friendly wargame designed to introduce players to the world of cryptography. Unlike Bandit, which focuses on Linux basics, Krypton takes you through different stages of encryption and decryption — from simple substitution ciphers to more advanced concepts.

In this walkthrough, I’ll cover all Krypton levels step by step. You’ll find not only the solutions but also the thought process, hints, and commands I used to solve each challenge. My goal is to make this guide useful for cybersecurity enthusiasts who are just starting out with cryptography and CTFs.

Krypton Level 0 → Level 1

(Updated: 12 August 2025)

Credentials

  • Username: No Need!
  • Password: No Need!

Connection

No Need!

Hints & Commands Learned

  • Base64 encoder

Steps to Solve

  1. Step 1 - Take the Base64 encode S1JZUFRPTklTR1JFQVQ= to website Base64 Decode to decode.
  2. Step 2 - Decode the encoded to get the password.
  3. Step 3 - Take the password to the next level.

Next Level Password

KRYPTONISGREAT

Krypton Level 1 → Level 2

(Updated: 12 August 2025)

Credentials

  • Username: krypton1
  • Password: KRYPTONISGREAT

Connection

ssh krypton1@krypton.labs.overthewire.org -p 2231

Hints & Commands Learned

  • ROT13 Encoder

Steps to Solve

  1. Step 1 - Use ssh to get access to OverTheWire labs.
  2. Step 2 - Call cd /krypton/krypton1 and cat krypton2 you will get a encoded one.
  3. Step 3 - Take it to Rot13 Decoder to decode the password.
  4. Step 4 - Take the password to the next level.

Next Level Password

ROTTEN

Krypton Level 2 → Level 3

(Updated: 12 August 2025)

Credentials

  • Username: krypton2
  • Password: ROTTEN

Connection

ssh krypton2@krypton.labs.overthewire.org -p 2231

Hints & Commands Learned

  • Decryption

Steps to Solve

  1. Step 1 - Use ssh to get access to OverTheWire labs.
  2. Step 2 - Call cd /krypton/krypton2 and cat krypton3 you will get a encoded one.
  3. Step 3 - Do like the example to create a temp directory and echo "AAABBB" >> test.txt and run /krypton/krypton2/encrypt ./test.txt to test the encrypt.
  4. Step 4 - cat test.txt and you will see something like OOOPPP so the logic is like a -> O, b -> B, …
  5. Step 5 - Run cat /krypton/krypton2/krypton3 |tr 'A-Z' 'O-ZA-N' to get the password based on the logic.
  6. Step 6 - Take the password to the next level.

Next Level Password

CAESARISEASY

Krypton Level 3 → Level 4

(Updated: 12 August 2025)

Credentials

  • Username: krypton3
  • Password: CAESARISEASY

Connection

ssh krypton3@krypton.labs.overthewire.org -p 2231

Hints & Commands Learned

  • Decryption

Steps to Solve

  1. Step 1 - Use ssh to get access to OverTheWire labs.
  2. Step 2 - Call cd /krypton/krypton3 and cat HINT1 HINT2 you will get the hints.
  3. Step 3 - Base on the README and hints we have to know the frequency of letters so call:
cat found1 found2 found3 | tr '[:upper:]' '[:lower:]' | grep -o . | sort | uniq -c | sort -nr

In order to get the frequency of words in 3 found files. 4. Step 4 - Call cat found1 found2 found3 | tr -d '\n' | fold -w1 | sort | uniq -c | sort -nr | awk '{printf $2}' to get the list of it without space and counts. Also, visit Wikipedia to get the list of most frequent letters from most to least. 5. Step 5 - Run cat /krypton/krypton3/krypton4 | tr 'SQJUBNGCDZVWMYTXKELAFIORHP' 'ETAONRISHDLFCMUGYPWBVKJXZQ' to get the password based on the logic.

Note: If the password doesn’t work in the next level you can try this instead cat /krypton/krypton3/krypton4 | tr 'SQJUBNGCDZVWMYTXKELAFIORHP' 'EATSORNIHCLDUPYFWGMBKVXQJZ'

  1. Step 6 - Take the password to the next level.

Next Level Password

BRUTE

Krypton Level 4 → Level 5

(Updated: 12 August 2025)

Credentials

  • Username: krypton4
  • Password: BRUTE

Connection

ssh krypton4@krypton.labs.overthewire.org -p 2231

Hints & Commands Learned

  • Vigenère cipher decryption

Steps to Solve Take a look at tutorial:

Next Level Password

CLEARTEXT

Krypton Level 5 → Level 6

(Updated: 12 August 2025)

Credentials

  • Username: krypton5
  • Password: CLEARTEXT

Connection

ssh krypton5@krypton.labs.overthewire.org -p 2231

Hints & Commands Learned

  • Decryption

Steps to Solve Take a look at tutorial:

Next Level Password

RANDOM

Krypton Level 6 → Level 7

(Updated: 12 August 2025)

Credentials

  • Username: krypton6
  • Password: RANDOM

Connection

ssh krypton6@krypton.labs.overthewire.org -p 2231

Hints & Commands Learned

  • Decryption

Steps to Solve Take a look at tutorial:

Next Level Password

NO MORE!