Visual cryptography is a technique that consists of hiding information (text/symbols/graphics) within two semi-transparent pictures (called layers). Overlaying both pictures exactly on top of one another, will reveal the hidden information.
Using this technique, it is impossible to retrieve any of the hidden information if you only have one of the two layers.
The technique consists of splitting each pixel of the original picture (information to hide) into 4 smaller squares as follows:
Note that the white squares on layer 1 and 2 are in fact transparent.
By repeating this process for each pixel of the original image, we obtain two layers with what appears to be random noise. However, overlapping these layers will reveal the black pixels of the original image.
You can drag the following layers to position them on top of one another and reveal the secret image:
Online Visual Cryptography
Use our online tool to create your own visual cryptography layers. To do so you will need to:
- Create a pixel art graphic on the first canvas. (Note that you can change the number of rows and columns for your canvas if needed)
- Press the encrypt button to generate both layers. The tool will also let you preview the result of overlaying both layers to reveal your pixel art.
- Press the “Download as PNG” buttons to download both layers (layer-1.png and layer-2.png)
- You can now insert both layers using a graphic editing software or an application software such as Powerpoint and try to reveal the secret pixel art by positioning both layers exactly on top of one another.