Ghost Font

Type a message, it can only be seen when the image is animating. Hit pause and see if you can still see it.

Try decoding a Ghost Font GIF frame by frame →

How it works

Every dot looks identical in a still image. One uniform field drifts one way outside the letter shapes, and a second statistically identical field drifts the opposite way inside them. Because both regions have the same density and appearance, the message can be seen by motion rather than in any single frame. It is not encryption, but it is a neat example of encoding information in “temporal change”.

Disclaimer

Don’t use this for anything important, it’s just a demo. Don’t use this for anything illegal, it’s obviously not secure and also I didn’t make this to help you do illegal shit. In practice this might work, but it probably won’t be effective for very long. It’s fairly easy to defeat. I’m sure someone could just write a method to defeat it, and I may add one later.

If you want your messages to be safe, use Signal, use good cryptography such as OpenSSL, learn your rights through the EFF’s Surveillance Self-Defense guide, or start with Crypto 101.