Испорченное селфи (Corrupted Selfie)

bug-makers

Task: a 1024x1024 selfie whose pixels were shuffled by an online photo filter, plus the URL of that service. Solution: chosen-plaintext oracle — upload a probe image where each pixel encodes its own flat index in RGB, read off the deterministic permutation from the lossless PNG output, then invert it (orig[dec]=shuffled) to recover the original image and read the flag.