Usually need lossless integer math for cryptography to work. So the form might be similar, but you’re working over finite fields (ie of integers mod some number

Usually need lossless integer math for cryptography to work. So the form might be similar, but you’re working over finite fields (ie of integers mod some number), not real numbers. (Okay, I have only a tenuous understanding of this myself. I’m a physicist, not a mathematician! Mathematicians are intimidating.)