> No one patented modular exponentiation, they patented an encryption algorithm that employs modular exponentiation.
Then I must ask: What invention is needed to invent the algorithm, once you know the math?
Is this a novel invention (no prior art about the same algorithmic idea being applied elsewhere)?
Is it non-obvious (a professional computer programmer couldn't be expected to come up with the algorithm, when presented with the math)?
I'm no expert, but I suspect that if you teach me the math behind a particular encryption scheme, then I could program the algorithm without too much difficulty.
>What invention is needed to invent the algorithm, once you know the math?
Math and algorithm are overloaded terms that often mean the same thing, so it's not possible to answer that question. However, to clarify what jandrewrogers meant: at the time modular exponentiation was a known mathematical construct; what was invented and patented was a new, previously unknown algorithm that used that mathematical construct as part of an encryption technique.
Now both can be seen as "math" or "algorithm", but the key difference is that the encryption algorithm has practical utility (i.e. providing security) whereas modular exponentiation by itself has none.
Then I must ask: What invention is needed to invent the algorithm, once you know the math?
Is this a novel invention (no prior art about the same algorithmic idea being applied elsewhere)?
Is it non-obvious (a professional computer programmer couldn't be expected to come up with the algorithm, when presented with the math)?
I'm no expert, but I suspect that if you teach me the math behind a particular encryption scheme, then I could program the algorithm without too much difficulty.