Note: dev.to modifies the image, the original image with the secret is the original post 🤘 I found a steganography challenge in a CTF last year that had me staring at a picture of a cat for two hours. The image looked completely normal; 800x600 pixels of an orange tabby sitting on a keyboard. No metadata anomalies, no appended ZIP files, no obvious artifacts. The flag was hiding in the least significant bits of the blue channel. Once I extracted it, the message was 43 characters long. The cat hadn't changed at all. That experience sent me down a rabbit hole. Steganography is one of those topics that sounds like movie-hacker fiction until you actually try it. Then you realize it's just math; and surprisingly simple math at that. What steganography actually is Steganography is the practice of hiding data inside other data so that nobody knows the hidden data exists. This is fundamentally different from cryptography.…