SHAdow generates, from two JPEG images, two different PDF files having the same SHA-1 sum.

Usage

./shadow.py <img1> <img2> <width> <height>

For example :

./shadow.py sun.jpg water.jpg 640 480

This generates shadow1.pdf and shadow2.pdf in the current folder.

Sample

Two images are provided :

./shadow.py tux.jpg troll.jpg 200 200

Constraints

The input images must have the same size, and their files must be smaller than 64K.

More

I wrote a blog article, in French: SHAdow.