# 🕵️‍♂️ Multi-Level Crypto Puzzle Solver

This Python script is a step-by-step cryptography challenge solver that decodes hidden messages using various encoding, encryption, and steganographic techniques. It progresses through **4 security challenge levels**, each building on common real-world techniques used in CTFs (Capture The Flag) or cryptographic puzzles.

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## 📜 Level 1: Base64 Decoding

```python
import base64
print(base64.b64decode("VGhlIGRyb3AgbG9jYXRpb24gaXMgaGlkZGVuIGluIHRoZSBuZXh0IGZpbGUu"))

• Decodes a Base64-encoded string.
• The message reveals a clue pointing to another file (message.txt) that contains the next piece of the puzzle.

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🔐 Level 2: ROT13 Cipher

def rot13(text): ...
with open("message.txt") as f:
    print(rot13(f.read()))

• Implements and applies a ROT13 substitution cipher to decrypt message.txt.
• This reveals a hint or perhaps another encrypted message.

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🔓 Level 3: AES Decryption with Brute Force

from Crypto.Cipher import AES
...
for b in range(256):
    key = known_key_prefix + bytes([b]) + b'\x00' * 7
    ...

• Reads aes_encrypted.bin, splits IV and ciphertext.
• Brute-forces the last byte of a partially known 16-byte AES key.
• Attempts to decrypt using AES-CBC mode and unpad()s the result.
• Prints out the successfully decrypted plaintext when the correct key is found.

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🖼️ Level 4: Steganography in PNG

with open("image.png", "rb") as f:
    data = f.read()
...
print(base64.b64decode(hidden_b64).decode())

• Reads a PNG file (image.png).
• Extracts all data after the PNG magic number \x89PNG\r\n\x1a\n.
• Decodes the hidden Base64-encoded string embedded after the PNG header.
• Prints the final decoded hidden message.

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🧩 Summary

This program walks through various classic CTF-style decoding stages:

Level	Technique	File Used	Concept Applied
1	Base64 Decoding	—	Simple data encoding
2	ROT13 Cipher	message.txt	Substitution cipher
3	AES Brute Force	aes_encrypted.bin	Cryptanalysis on AES keys
4	PNG Stego	image.png	Steganography + Base64 extraction

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🧠 Requirements

• Python 3.x
• pycryptodome (for AES decryption)

Install dependencies:

pip install pycryptodome

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💡 Usage

Place the required files (message.txt, aes_encrypted.bin, image.png) in the same directory as the script and run:

python Cracked_Version.py

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🔒 Educational Purpose Only

This project is intended for educational and ethical hacking learning purposes only. Do not use these techniques for unauthorized access or illegal activities.

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