Open Source/Open Result / One-off-api calls

One of the things that makes me really enthousiastic about Ethereum & crypto like it in general, is that it allows easy payment for one-off computation, rather than API-calls which require subscribtions.

I have a question though: Is it somehow possible to execute code that is not opensource/visible on ethereum?

Say you want to provide the output of some computation, based on some input parameters, but you do not want to show how this is calculated/determined (possibly because you make use of sensitive data). Would this be possible and if so how?

When I look around oftentimes the contracts are shown, for good measure w.r.t. where the money/eth is going, but in my case I mean a separate computation that is only used for input-output.

I'm thinking about a programme that creates the blueprint for some algorithmic art, for which I want to send payment to the originator of the idea automatically, as well as 2 popularizers (with like a 1% cut for myself for doing the programming work), but I'm worried someone will just fork/copy the blueprint code.

Please redirect me of there is a better place to ask about this.