Puzzled: Challenge Setup

We get an image of a scrambled QR-Code, and the code that was used to generate it.

from PIL import Image
import random

def shuffle3x3GridImage(image_path, output_path):
    # Open the image
    original_image = Image.open(image_path)
    
    # Get the size of the image
    width, height = original_image.size
    assert(width == 234 and height == 234)
    
    # Calculate the size of each grid cell
    cell_width = width // 3
    cell_height = height // 3
    
    # Create a new image to store rearranged pieces
    new_image = Image.new("RGB", (width, height))
    
    # Create a list to store shuffled grid positions
    positions = [(x, y) for x in range(3) for y in range(3)]
    random.shuffle(positions)
    
    # Split the original image into 16 pieces and rearrange them
    for i, pos in enumerate(positions):
        # Calculate the coordinates of the current grid cell
        x1 = pos[0] * cell_width
        y1 = pos[1] * cell_height
        x2 = x1 + cell_width
        y2 = y1 + cell_height
        
        # Crop the corresponding part of the original image
        cropped_piece = original_image.crop((x1, y1, x2, y2))
        
        # Calculate the coordinates to paste the cropped piece
        new_x = (i % 3) * cell_width
        new_y = (i // 3) * cell_height
        
        # Paste the cropped piece onto the new image
        new_image.paste(cropped_piece, (new_x, new_y))
    
    # Save the rearranged image
    new_image.save(output_path)


key = "Not the real key!"
random.seed(key)
shuffle3x3GridImage("fullVersion25QRcode.png", "puzzledVersion25QRcode.png")

Solving

The comment says it cuts it into 16 pieces, I am pretty sure it's just 9, but whatever. We were all tired, no need to do math or thinking. Just reuse the same code for the solve script.

Basic idea: try all possible combinations and see which ones are valid.

Solve Script

from PIL import Image
import random
import itertools as it
from pyzbar import pyzbar

def original_rearrange_fun(positions, cell_width, cell_height, width, height, original_image):
    # Create a new image to store rearranged pieces
    new_image = Image.new("RGB", (width, height))
    # Split the original image into 16 pieces and rearrange them
    for i, pos in enumerate(positions):
        # Calculate the coordinates of the current grid cell
        x1 = pos[0] * cell_width
        y1 = pos[1] * cell_height
        x2 = x1 + cell_width
        y2 = y1 + cell_height
        
        # Crop the corresponding part of the original image
        cropped_piece = original_image.crop((x1, y1, x2, y2))
        
        # Calculate the coordinates to paste the cropped piece
        new_x = (i % 3) * cell_width
        new_y = (i // 3) * cell_height
        
        # Paste the cropped piece onto the new image
        new_image.paste(cropped_piece, (new_x, new_y))
    return new_image

def brute(image_path):
    # Open the image
    original_image = Image.open(image_path)
    
    # Get the size of the image
    width, height = original_image.size
    assert(width == 234 and height == 234)
    
    # Calculate the size of each grid cell
    cell_width = width // 3
    cell_height = height // 3

    positions = [(x, y) for x in range(3) for y in range(3)]
    for attempt in it.permutations(positions, len(positions)):
        print(f"{attempt=}")
        original_image = Image.open(image_path)
        image_attempt = original_rearrange_fun(attempt, cell_width, cell_height, width, height, original_image)
        bruh = pyzbar.decode(image_attempt, symbols=[pyzbar.ZBarSymbol.QRCODE])
        if bruh:
            print(bruh)
            breakpoint()
    


if __name__ == "__main__":
    brute("puzzledVersion25QRcode.png")

Output

attempt=((0, 1), (0, 2), (1, 2), (0, 0), (2, 2), (2, 0), (1, 0), (1, 1), (2, 1))
[Decoded(data=b'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. INS{Im-puzzl3d-6c2bd4d3-e739-4f8d-b8cd-6bd663bde735} Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.', type='QRCODE', rect=Rect(left=0, top=0, width=234, height=234), polygon=[Point(x=0, y=0), Point(x=0, y=234), Point(x=233, y=233), Point(x=234, y=0)], quality=1, orientation=None)]
> /home/generic/Downloads/ctf/inso/puzzled/solve.py(41)brute()
-> for attempt in it.permutations(positions, len(positions)):