On the possibility of classical client blind quantum computing
This work addresses the challenge of secure quantum computing for classical clients, representing a novel approach rather than an incremental improvement.
The paper tackles the problem of enabling classical clients to perform secure delegated quantum computing without quantum communication, by introducing a delegated pseudo-secret random qubit generator (PSRQG) functionality. It presents a concrete protocol (QFactory) using Learning-With-Errors to achieve this, proving security in a quantum-honest-but-curious setting.
We define the functionality of delegated pseudo-secret random qubit generator (PSRQG), where a classical client can instruct the preparation of a sequence of random qubits at some distant party. Their classical description is (computationally) unknown to any other party (including the distant party preparing them) but known to the client. We emphasize the unique feature that no quantum communication is required to implement PSRQG. This enables classical clients to perform a class of quantum communication protocols with only a public classical channel with a quantum server. A key such example is the delegated universal blind quantum computing. Using our functionality one could achieve a purely classical-client computational secure verifiable delegated universal quantum computing (also referred to as verifiable blind quantum computation). We give a concrete protocol (QFactory) implementing PSRQG, using the Learning-With-Errors problem to construct a trapdoor one-way function with certain desired properties (quantum-safe, two-regular, collision-resistant). We then prove the security in the Quantum-Honest-But-Curious setting and briefly discuss the extension to the malicious case.