A computation can be performed when no participant is permitted to see the inputs. Three architectures have reached production in the past decade.
Fully homomorphic encryption operates on ciphertext directly; Gentry's 2009 construction was a billion times slower than plaintext, and fifteen years of engineering have cut four orders of magnitude off that overhead. Secure multi-party computation splits inputs across parties, as MuSig2 and FROST do for Schnorr signatures on Bitcoin.
Fully homomorphic encryption operates on ciphertext directly; Gentry's 2009 construction was a billion times slower than plaintext, and fifteen years of engineering have cut four orders of magnitude off that overhead. Secure multi-party computation splits inputs across parties, as MuSig2 and FROST do for Schnorr signatures on Bitcoin.
