Author: Kavya Bhat
Flag: CTF{th@nk2_f0r_h3lping}
Oh no! I broke this framed image. Unless you can magically put it together, I’m in big trouble.
Flag format: CTF{...}
Unzipping the file pieces.zip presents a folder with 400 black-and-white jpg files (could it be a QR code?). These are labeled in the order 0101, 0102, ... 2020 which gives us a clue that it might be a matrix of some kind. Considering the phrase broken pieces and the idea of putting it together, a quick search reveals the ImageMagick tool, which allows you to work with images from the command line.
magick montage is one such command that has an option called -tile. This helps merge multiple images into a matrix of the required width and height.
Using this command: montage -tile 20x20 -geometry +0+0 qr.jpg generates a merged image named qr.jpg.
The option -tile 20x20 merges the images such that it has a width and height of exactly 20 files each.
The option -geometry +0+0 ensures that no border is present between individual images.
The obtained image is a QR code, which on scanning reveals the text th@nk2_f0r_h3lping.
The flag to this challenge would be CTF{th@nk2_f0r_h3lping}.