Hiding data from humans and computers in GIF files

That’s right. No extra data, no changes to the image. All the pixels and colours are exactly the same. Any data you want inside a GIF without any trace. But how? I’m glad you asked.

During highschool I was interested in steganography, the study of hiding messages in plain sight. I had just finished a simulation project that encoded GIFs, so I was still in the headspace of the GIF codec. I began tinkering with the different elements and found an area I wanted to manipulate. Here’s how I encoded 127 bytes into a GIF without changing the file size.

Why is this special?

2 Points