I have trouble understanding how Reed-Solomon coding can produce same number of output bits than the input was.
Twofish uses this technique. I've read the paper, but still can't quite understand how the flattening works. In my understanding, RS should add redundant bits, and the output must be larger than the input. What am I missing?
In addition, how is the MDS matrix constructed from RS coding? It seems that it was constructed using clever heuristics.