  To date, blind quantum computing demonstrations require clients to have weak
quantum devices. Here we implement a proof-of-principle experiment for
completely classical clients. Via classically interacting with two quantum
servers that share entanglement, the client accomplishes the task of having the
number 15 factorized by servers who are denied information about the
computation itself. This concealment is accompanied by a verification protocol
that tests servers' honesty and correctness. Our demonstration shows the
feasibility of completely classical clients and thus is a key milestone towards
secure cloud quantum computing.
