🔐 Can you crack the cipher that stumped cryptographers for 300 years?

Master spies have hidden their most sensitive secrets using this legendary polyalphabetic cipher, but there's a twist - the key itself is concealed within innocent-looking images! 🖼️ Combine classical cryptanalysis with modern steganographic techniques to uncover layers of hidden information. 🕵️ This challenge demands both historical cryptographic knowledge and cutting-edge digital forensics skills to reveal the ultimate secret! 🔍

Flags

Points

Challenge

Solution Available

Pro Exclusive

Start Lab Environment

~1-2 min setup

AWS dedicated

Private instance

Industry standard

Challenge

🔐 Vigenère Stego Hunt - Complete Solution

Objective: Extract the hidden key from the image using steganography, then use it to decrypt the Vigenère cipher and reveal the flag.

🔍 Step 1: Steganographic Analysis

The challenge provides an image file that contains hidden data using LSB (Least Significant Bit) steganography. Extract the hidden key using steganographic tools:

Method 1: Using zsteg
zsteg secret_key.png

Method 2: Using steghide
steghide extract -sf secret_key.png

Method 3: Using Python script
Extract LSB data from the red channel of image pixels to reveal hidden text.

🔍 Step 2: Extracting the Vigenère Key

The steganographic analysis reveals the hidden key: CRYPTOKEY

Key Discovery: The key 'CRYPTOKEY' is embedded in the least significant bits of the image pixels. This demonstrates how steganography can securely distribute cipher keys.

🔍 Step 3: Vigenère Cipher Decryption

With the key 'CRYPTOKEY', decrypt the ciphertext 5E22R314BS144Y75853SN168F8BFVBQY using standard Vigenère decryption:

Decryption Process:
Ciphertext: 5E22R314BS144Y75853SN168F8BFVBQY
Key: CRYPTOKEY (repeated)
Result: 5C22A314DD144F75853ED168B8DDEDBF

Online Tools:
• https://www.dcode.fr/vigenere-cipher
• https://cryptii.com/pipes/vigenere-cipher

🔍 Step 4: Formatting the Flag

The decrypted text 5C22A314DD144F75853ED168B8DDEDBF is the UUID without hyphens. Add hyphens at the standard UUID positions:

Final Flag: The complete UUID flag is revealed after adding hyphens to the decrypted text.

📚 Learning Points

Steganography: LSB techniques for hiding data in images
Classical Cryptography: Vigenère cipher mechanics and decryption
Multi-layer Security: Combining steganography with cryptography
UUID Format: Understanding standard UUID structure with hyphens

Security Note: This challenge demonstrates how multiple security layers can protect sensitive data, requiring knowledge of both steganographic and cryptographic techniques.

Labs / Vigenere Stego Hunt