[aobbpwsh] Steganography with the P pentomino rep-tile

The P pentomino can be tiled with 4 smaller copies of itself in two distinct ways.  Let this encode 1 bit.

Number the 4 smaller copies, then proceed breadth first (or depth first, if you know the length of data in advance) encoding further bits by recursively tiling the smaller copies.

The numbering could constitute a cryptographic key.  There are simple ways of doing it, but also more complicated, perhaps depending on the bit encoded, orientation, parent's orientation.

It's a bit like a space filling curve how linear data gets disseminated over two dimensions.