To encrypt information using visual cryprography, two black and white images are created from the image containing the information, which must be superimposed in order to obtain the original information again.

As an additional option, an image can be used as a key to ensure standardised encryption – e.g. in the context of multis.
To encode/decode colour images, a pixel/pixel is considered transparent if it is transparent or the colour value is > 128 (0..255).
Decrypt
The GC Wizard allows you to load a graphic from the photo gallery, from the device or from the Internet.

To decode, upload the two images to be overlaid and, if required, an offset in X and Y. After clicking on “Calculate”, the image is assembled.
Clicking on “Clear image” removes the background noise.
The following functions are available in the display of the generated image:
![]() | Switch to full screen mode |
![]() | Fit image (after zooming) |
![]() | Save single image |
![]() | Open in: – Exif/Metadata Viewer – Color correction – Hex Viewer – Search for Hidden Data |

Encrypt
The GC Wizard allows you to load a graphic from the device or from the Internet.

After a file has been loaded, an offset in X and Y can be specified. It is also possible to enter a scaling.
The result is the two images, which have to be superimposed to decode them in order to get the original view again.
The following functions are available in the display of the generated images:
![]() | Switch to full screen mode |
![]() | Fit image (after zooming) |
![]() | Save single image |
![]() | Open in: – Exif/Metadata Viewer – Color correction – Hex Viewer – Search for Hidden Data |

Encrypt with a Key
The idea is as follows: we have a normal visual cryptographic image pair. Both were created randomly.
Now a second pair is to be created – with an image of the first pair (let’s call it key). This means that the key image is loaded to encrypt the second image. This makes it possible to create a “key image” – for example at the start of a multi – and use it to encrypt different images.
This allows you to place the key in different stages and decrypt different clues with the same key image. So:
1. create a pair normally for stage 1
2. switch to create with key, load the key image and create the second image. And so on …
