Hide algorithm and variables

Question

I have some variables in my algorithm that I would not want others to see.

Party A would write an algorithm which will use my variables. But party's A algorithm should remain hidden i.e. I should not see it.

I run A's algorithm which uses my variables and it produces an output.

In reality the problem is that Party A might be an adversary. There are lots of parties writing algorithms so there is not only one party A. We can assume that most of the parties are not bad.

Is there a way to prevent my variables from leaking out to Party A?

If someone knows a paper about this could you point me in the right direction. The solution can also be one that is indistinguishably hard.

Answer 1

You are looking for something called fully homomorphic encryption.

The gist of it is that party A can compute stuff using your variables without knowing your variables (mind blown, I know).

It would be using special encryption such that you can do operations on the ciphertext such that the decrypted result is the same as if you had done the operations to the plaintext values.

In other words: E(x) + E(y) = E(x + y)

As for implementations, I recommend looking into tfhe, etc.

As for papers, this one is the among the most well-known although it's techniques have been improved upon since it was published: https://crypto.stanford.edu/craig/