Caesar Shift Decoder

🏛️ Can you crack Julius Caesar's secret military code?

Challenge 23 Nov 2025 Pro Exclusive Solution Available

Ancient Roman generals relied on this ingenious cipher to protect their most sensitive battle plans and strategic communications. 🛡️ What stumped enemy cryptographers for centuries now challenges modern code breakers to uncover hidden messages through mathematical precision and pattern analysis. 🔍 Master the techniques that shaped the foundation of modern cryptography and prove your skills against this timeless encryption method! ⚔️

Flags

Points

71%

Success Rate

Start Your Challenge

~1-2 min setup

Dedicated server

Private instance

Industry standard

This solution is for Flags Mode

This walkthrough explains how to hack the lab and capture the flags. For help with Learning Mode questions, use the Request Hint button next to each question.

Challenge

🏛️ Caesar Shift Decoder - Complete Solution

Objective: Decode the Caesar cipher by determining the correct shift value and revealing the hidden flag.

🔍 Step 1: Identify the Encrypted Message

The challenge presents this encrypted flag:

Encrypted: 364m41i4-hjk6-4002-904i-6186mkijl3m3

Notice that numbers and hyphens remain unchanged, while only letters are encrypted.

🔍 Step 2: Determine the Shift Value

The correct shift value is 7. This means each letter was moved forward 7 positions in the alphabet during encryption.

Key Insight: To decrypt, we need to shift each letter BACKWARD by 7 positions.

🔍 Step 3: Manual Decryption Process

Let's decode each letter step by step:

Position	Encrypted	Shift Back 7	Decrypted
4th	m	m(-7) = f	f
7th	i	i(-7) = b	b
10th	h	h(-7) = a	a
11th	j	j(-7) = c	c
12th	k	k(-7) = d	d
17th	i	i(-7) = b	b
22nd	m	m(-7) = f	f
23rd	k	k(-7) = d	d
24th	i	i(-7) = b	b
25th	j	j(-7) = c	c
26th	l	l(-7) = e	e
28th	m	m(-7) = f	f
29th	m	m(-7) = f	f

🔍 Step 4: Complete Decryption

Applying the shift of -7 to all encrypted letters:

Encrypted: 364m41i4-hjk6-4002-904i-6186mkijl3m3
Decrypted: 364f41b4-acd6-4002-904b-6186fdbce3f3

🔍 Step 5: Verification

The decrypted result is a valid UUID format containing only hexadecimal characters (0-9, a-f):

Pattern: 8-4-4-4-12 characters separated by hyphens ✓
Characters: Only 0-9 and a-f (valid hexadecimal) ✓
Format: Proper UUID structure ✓

🎯 Final Answer

Flag: 364f41b4-acd6-4002-904b-6186fdbce3f3

🔍 Alternative Methods

You could also solve this using:

// JavaScript in browser console
let cipher = '364m41i4-hjk6-4002-904i-6186mkijl3m3';
let decoded = cipher.replace(/[a-z]/g, char => 
  String.fromCharCode((char.charCodeAt(0) - 97 - 7 + 26) % 26 + 97)
);
console.log(decoded); // 364f41b4-acd6-4002-904b-6186fdbce3f3

📚 Learning Points

Shift Value: Caesar cipher used shift of 7 positions
Decryption: Reverse the encryption by shifting backward
Pattern Recognition: Valid UUID format confirms correct decryption
Brute Force: Only 25 possible shifts make testing feasible
Character Preservation: Numbers and symbols remain unchanged