Not sure, I think first image is square or geometric Kufic (sometimes called "Satrancli Kûfi" in Turkish) of course looks quite different than typical Kufic script.

> There's some good examples on wikipedia as well: https://en.wikipedia.org/wiki/

This is not the link you intended...

I always found Kufi to be a form of space-filling curves[0], which was the original purpose: a form of decoration that can fill a surface such as edges around a building[1, 2], without depicting humans in stone, a form of art historically forbidden in Islam due the prevalence of statue idolatry at the time. Hence the prevalence of geometry (Zellij [3]) and calligraphy in areas historically islamic.

Hilbert curves [4] could be the substrate (the coordinate system), and Kufi writing could be indeed encoded information maybe by XORing each point between the curve and the kufi word.

I'm just blabbering around. But it's difficult to disassociate the two in my mind.

0: https://www.shutterstock.com/image-vector/kufi-ayat-kursi-al...

1: https://i0.wp.com/majnouna.com/wordpress/wp-content/uploads/...

2: https://i.pinimg.com/236x/f2/f7/e9/f2f7e99d6bfe75042313adbe6...

3: https://zellige.info/

4: https://www.researchgate.net/profile/Christoph-Schierz/publi...

It varies, the example from the Topkapi Scroll, with the tile-like patterns of triangles and swastikas, took me a minute to recognize (but it's been 25yr since I took Arabic as an undergrad). Some of the other examples are fun, the shahada that looks like minarets is actually mirrored text, so it reads backwards from the left and normally (well, it's super-stylized) from the right.

Some more easily than others.

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do not tell this everywhere. it's a secret.

Because they can. I've encountered plenty of pages like this and it would seem that doing so is risk free.