Semiquantum key distribution with secure delegated quantum computation

Semiquantum key distribution allows a quantum party to share a random key with a classical party who only can prepare and measure qubits in the computational basis or reorder some qubits when he has access to a quantum channel. In this work, we present a protocol where a secret key can be established between a quantum user and an almost classical user who only needs the quantum ability to access quantum channels, by securely delegating quantum computation to a quantum server. We show the proposed protocol is robust even when the delegated quantum server is a powerful adversary, and is experimentally feasible with current technology. As one party of our protocol is the most quantum resource efficient, it can be more practical and significantly widen the applicability scope of quantum key distribution.