Consider two business associates, Adam and Karl, who want to arrange an exchange of information.
Adam has knowledge of two secret numbers k
and j
. He must never disclose their values to anyone.
Karl wants to calculate a function of these two numbers:
f(k, j) = k + j
Adam decides that it is OK for Karl to know the value produced by this function, but not the inputs. This poses a tricky problem. Karl is not interested in the input values, and though he trusts Adam to be honest about them, he wants some proof that his calculation is being performed correctly. Puzzled by these seemingly irreconcilable constraints, they decide to call upon some mutual contacts for help.