[a-dub]

this is funny. when i first learned the algorithm, i found some matlab code that computes it with bit vectors. i added support for displaying them as an image and used the movie feature to generate step by step movies to build intuition.

nice to see someone build something polished that visualizes it in the same way. once you look at the mechanics for each round of the compression function and see the bits get swirled around for yourself, it starts to make intuitive sense.

the other big intuitions are of course, the trapdoor nature of add mod 2^32 (which is implicit in unsigned integer overflow on many machines) and the fact that some operations (like xor) operate in galois field 2, while others (like addition) operate in galois field 32 and the repeated stacking of the operations in different fields gives the function it's nonlinear trapdoor property.

i remember reading a pretty good paper on the arx (add, rotate, xor) family of ciphers back in the day (sort of in the vein of, is that all you need?)...